Add Radio and Toggle form fields

Closes #160. Adds two new form field components:

- FormFieldRadio: renders a string-Enum/Literal field as a radio button
  group. Triggered by `Radio()` (or json_schema_extra={"format": "radio"})
  on the Pydantic field. Supports `inline` for horizontal layout.
- FormFieldToggle: dedicated on/off switch component. Triggered by
  `Toggle()` (or json_schema_extra={"format": "toggle"}). Optional
  on_label / off_label render next to the switch.

Multi-value fields (list[Enum]) annotated with Radio() fall back to the
existing select component, since radios can't represent multi-select.

Frontend:
- src/npm-fastui/src/components/FormField.tsx: new FormFieldRadioComp
  and FormFieldToggleComp following the existing FormFieldBooleanComp /
  FormFieldSelectVanillaComp patterns. Pre-computes useClassName values
  to satisfy react-hooks/rules-of-hooks.
- src/npm-fastui/src/components/index.tsx: wires the new types into the
  AnyComp switch.
- src/npm-fastui/src/models.d.ts: matching TypeScript interfaces.
- src/npm-fastui-bootstrap/src/index.tsx: Bootstrap classNameGenerator
  cases for `form-check`, `form-switch`, radio sub-elements.
- src/npm-fastui-bootstrap/src/Radio.tsx, Toggle.tsx: thin re-export
  wrappers (matches the layout of modal.tsx / navbar.tsx).

Python:
- src/python-fastui/fastui/components/forms.py: FormFieldRadio /
  FormFieldToggle Pydantic models with `type` discriminator.
- src/python-fastui/fastui/forms.py: Radio() / Toggle() helper
  functions that mirror the existing Textarea() helper.
- src/python-fastui/fastui/json_schema.py: dispatch on format='radio'
  (string + enum) and format='toggle' (boolean). Also preserve outer
  `format` keys when dereferencing $ref so per-field overrides survive.

Tests:
- src/python-fastui/tests/test_forms.py: 5 new tests covering radio
  field schema output, radio submit, invalid value, toggle schema
  output, and the multi-radio fallback to select.

Author: Mukunda Katta

src/npm-fastui-bootstrap/src/Radio.tsx

@@ -0,0 +1,15 @@
+import { FC } from 'react'
+import { components, models } from 'fastui'
+
+/**
+ * Bootstrap-flavoured wrapper around the core `FormFieldRadioComp`.
+ *
+ * The radio button group itself is rendered by the core npm-fastui package; the
+ * styling for Bootstrap is supplied via the `classNameGenerator` in this
+ * package's `index.tsx`. This wrapper exists so consumers can plug a Radio in
+ * via `customRender` (or import it directly) without having to reach into
+ * `fastui/components`. Matches the file layout of `modal.tsx` / `navbar.tsx`.
+ */
+export const Radio: FC<models.FormFieldRadio> = (props) => {
+  return <components.FormFieldRadioComp {...props} />
+}

src/npm-fastui-bootstrap/src/Toggle.tsx

@@ -0,0 +1,15 @@
+import { FC } from 'react'
+import { components, models } from 'fastui'
+
+/**
+ * Bootstrap-flavoured wrapper around the core `FormFieldToggleComp`.
+ *
+ * The toggle (on/off switch) itself is rendered by the core npm-fastui package;
+ * Bootstrap styling is supplied via the `classNameGenerator` in this package's
+ * `index.tsx`. The wrapper exists so consumers can plug a Toggle in via
+ * `customRender` (or import it directly) without having to reach into
+ * `fastui/components`. Matches the file layout of `modal.tsx` / `navbar.tsx`.
+ */
+export const Toggle: FC<models.FormFieldToggle> = (props) => {
+  return <components.FormFieldToggleComp {...props} />
+}

src/npm-fastui-bootstrap/src/index.tsx

@@ -78,16 +78,18 @@ export const classNameGenerator: ClassNameGenerator = ({
     case 'FormFieldInput':
     case 'FormFieldTextarea':
     case 'FormFieldBoolean':
+    case 'FormFieldToggle':
+    case 'FormFieldRadio':
     case 'FormFieldSelect':
     case 'FormFieldSelectSearch':
     case 'FormFieldFile':
       switch (subElement) {
         case 'textarea':
         case 'input':
           return {
-            'form-control': type !== 'FormFieldBoolean',
+            'form-control': type !== 'FormFieldBoolean' && type !== 'FormFieldToggle' && type !== 'FormFieldRadio',
             'is-invalid': props.error != null,
-            'form-check-input': type === 'FormFieldBoolean',
+            'form-check-input': type === 'FormFieldBoolean' || type === 'FormFieldToggle' || type === 'FormFieldRadio',
           }
         case 'select':
           return 'form-select'
@@ -97,17 +99,35 @@ export const classNameGenerator: ClassNameGenerator = ({
           if (props.displayMode === 'inline') {
             return 'visually-hidden'
           } else {
-            return { 'form-label': true, 'fw-bold': !!props.required, 'form-check-label': type === 'FormFieldBoolean' }
+            return {
+              'form-label': true,
+              'fw-bold': !!props.required,
+              'form-check-label': type === 'FormFieldBoolean' || type === 'FormFieldToggle',
+            }
           }
         case 'error':
           return 'invalid-feedback'
         case 'description':
           return 'form-text'
+        case 'radio':
+          return 'form-check'
+        case 'radio-group':
+          return ''
+        case 'radio-group-inline':
+          return 'd-flex gap-3 flex-wrap'
+        case 'radio-label':
+          return 'form-check-label'
+        case 'toggle-labels':
+          return 'ms-2 small text-muted'
+        case 'toggle-on':
+          return 'ms-1'
+        case 'toggle-off':
+          return 'me-1'
         default:
           return {
             'mb-3': true,
-            'form-check': type === 'FormFieldBoolean',
-            'form-switch': type === 'FormFieldBoolean' && props.mode === 'switch',
+            'form-check': type === 'FormFieldBoolean' || type === 'FormFieldToggle',
+            'form-switch': type === 'FormFieldToggle' || (type === 'FormFieldBoolean' && props.mode === 'switch'),
           }
       }
     case 'Navbar':

src/npm-fastui/src/components/FormField.tsx

@@ -6,6 +6,8 @@ import type {
   FormFieldInput,
   FormFieldTextarea,
   FormFieldBoolean,
+  FormFieldToggle,
+  FormFieldRadio,
   FormFieldFile,
   FormFieldSelect,
   FormFieldSelectSearch,
@@ -100,6 +102,106 @@ export const FormFieldBooleanComp: FC<FormFieldBooleanProps> = (props) => {
   )
 }
 
+interface FormFieldToggleProps extends FormFieldToggle {
+  onChange?: PrivateOnChange
+}
+
+export const FormFieldToggleComp: FC<FormFieldToggleProps> = (props) => {
+  const { name, required, locked, onChange, onLabel, offLabel } = props
+  // hooks must be called unconditionally; precompute every class name before render.
+  const containerClass = useClassName(props)
+  const inputClass = useClassName(props, { el: 'input' })
+  const labelsClass = useClassName(props, { el: 'toggle-labels' })
+  const onClass = useClassName(props, { el: 'toggle-on' })
+  const offClass = useClassName(props, { el: 'toggle-off' })
+
+  return (
+    <div className={containerClass}>
+      <Label {...props} />
+      <input
+        type="checkbox"
+        role="switch"
+        className={inputClass}
+        defaultChecked={!!props.initial}
+        id={inputId(props)}
+        name={name}
+        required={required}
+        disabled={locked}
+        aria-describedby={descId(props)}
+        onChange={onChange}
+      />
+      {/* Optional on/off labels render after the switch so screen readers announce them
+          alongside the standard label. They are visual hints, not separate inputs. */}
+      {(onLabel || offLabel) && (
+        <span className={labelsClass}>
+          {offLabel && <span className={offClass}>{offLabel}</span>}
+          {onLabel && <span className={onClass}>{onLabel}</span>}
+        </span>
+      )}
+      <ErrorDescription {...props} />
+    </div>
+  )
+}
+
+interface FormFieldRadioProps extends FormFieldRadio {
+  onChange?: PrivateOnChange
+}
+
+export const FormFieldRadioComp: FC<FormFieldRadioProps> = (props) => {
+  const { name, required, locked, options, initial, onChange, inline } = props
+  const groupId = inputId(props)
+  // hooks must be called unconditionally; precompute every class name before render.
+  const containerClass = useClassName(props)
+  const radioGroupClass = useClassName(props, { el: 'radio-group' })
+  const radioGroupInlineClass = useClassName(props, { el: 'radio-group-inline' })
+  const radioClass = useClassName(props, { el: 'radio' })
+  const inputClass = useClassName(props, { el: 'input' })
+  const radioLabelClass = useClassName(props, { el: 'radio-label' })
+
+  // Flatten any select groups so we can render a flat list of <input type="radio"> rows.
+  // We don't currently render group separators because the radio control isn't a great
+  // place to display section headings — the maintainer can add that later if needed.
+  const flatOptions: SelectOption[] = []
+  for (const opt of options) {
+    if ('options' in opt) {
+      flatOptions.push(...opt.options)
+    } else {
+      flatOptions.push(opt)
+    }
+  }
+
+  return (
+    <div className={containerClass} role="radiogroup" aria-labelledby={`${groupId}-label`}>
+      <Label {...props} />
+      <div className={inline ? radioGroupInlineClass : radioGroupClass}>
+        {flatOptions.map((opt, i) => {
+          const optionId = `${groupId}-${i}`
+          return (
+            <div key={opt.value} className={radioClass}>
+              <input
+                type="radio"
+                className={inputClass}
+                id={optionId}
+                name={name}
+                value={opt.value}
+                defaultChecked={initial === opt.value}
+                required={required && i === 0}
+                disabled={locked}
+                aria-describedby={descId(props)}
+                onChange={onChange}
+              />
+              <label htmlFor={optionId} className={radioLabelClass}>
+                {opt.label}
+              </label>
+            </div>
+          )
+        })}
+      </div>
+      <ErrorDescription {...props} />
+    </div>
+  )
+}
+
 interface FormFieldFileProps extends FormFieldFile {
   onChange?: PrivateOnChange
 }
@@ -329,6 +431,8 @@ export type FormFieldProps =
   | FormFieldInputProps
   | FormFieldTextareaProps
   | FormFieldBooleanProps
+  | FormFieldToggleProps
+  | FormFieldRadioProps
   | FormFieldFileProps
   | FormFieldSelectProps
   | FormFieldSelectSearchProps

src/npm-fastui/src/components/index.tsx

@@ -18,6 +18,8 @@ import {
   FormFieldInputComp,
   FormFieldTextareaComp,
   FormFieldBooleanComp,
+  FormFieldToggleComp,
+  FormFieldRadioComp,
   FormFieldSelectComp,
   FormFieldSelectSearchComp,
   FormFieldFileComp,
@@ -55,6 +57,8 @@ export {
   FormComp,
   FormFieldInputComp,
   FormFieldBooleanComp,
+  FormFieldToggleComp,
+  FormFieldRadioComp,
   FormFieldSelectComp,
   FormFieldSelectSearchComp,
   FormFieldFileComp,
@@ -134,6 +138,10 @@ export const AnyComp: FC<FastProps> = (props) => {
         return <FormFieldTextareaComp {...props} />
       case 'FormFieldBoolean':
         return <FormFieldBooleanComp {...props} />
+      case 'FormFieldToggle':
+        return <FormFieldToggleComp {...props} />
+      case 'FormFieldRadio':
+        return <FormFieldRadioComp {...props} />
       case 'FormFieldFile':
         return <FormFieldFileComp {...props} />
       case 'FormFieldSelect':

src/npm-fastui/src/models.d.ts

@@ -36,6 +36,8 @@ export type FastProps =
   | FormFieldInput
   | FormFieldTextarea
   | FormFieldBoolean
+  | FormFieldToggle
+  | FormFieldRadio
   | FormFieldFile
   | FormFieldSelect
   | FormFieldSelectSearch
@@ -559,6 +561,8 @@ export interface Form {
     | FormFieldInput
     | FormFieldTextarea
     | FormFieldBoolean
+    | FormFieldToggle
+    | FormFieldRadio
     | FormFieldFile
     | FormFieldSelect
     | FormFieldSelectSearch
@@ -641,6 +645,50 @@ export interface FormFieldBoolean {
   mode?: 'checkbox' | 'switch'
   type: 'FormFieldBoolean'
 }
+/**
+ * Form field for an on/off toggle (switch) input.
+ */
+export interface FormFieldToggle {
+  name: string
+  title: string[] | string
+  required?: boolean
+  error?: string
+  locked?: boolean
+  description?: string
+  displayMode?: 'default' | 'inline'
+  className?:
+    | string
+    | ClassName[]
+    | {
+        [k: string]: boolean
+      }
+  initial?: boolean
+  onLabel?: string
+  offLabel?: string
+  type: 'FormFieldToggle'
+}
+/**
+ * Form field for a radio button group.
+ */
+export interface FormFieldRadio {
+  name: string
+  title: string[] | string
+  required?: boolean
+  error?: string
+  locked?: boolean
+  description?: string
+  displayMode?: 'default' | 'inline'
+  className?:
+    | string
+    | ClassName[]
+    | {
+        [k: string]: boolean
+      }
+  options: SelectOptions
+  initial?: string
+  inline?: boolean
+  type: 'FormFieldRadio'
+}
 /**
  * Form field for file input.
  */
@@ -748,6 +796,8 @@ export interface ModelForm {
     | FormFieldInput
     | FormFieldTextarea
     | FormFieldBoolean
+    | FormFieldToggle
+    | FormFieldRadio
     | FormFieldFile
     | FormFieldSelect
     | FormFieldSelectSearch