Add `@appica/ui-svelte` (Svelte 5 port of `@appica/ui-react`)

[triadmoko]

Summary

Add @appica/ui-svelte as a sibling package to @appica/ui-react in this monorepo: same design tokens and public component set, implemented in Svelte 5 (runes) instead of React.

CONTRIBUTING.md already treats extra framework packages as expected (pnpm dev "as more packages land"), but the documented workflow, playground, and repo layout are still React-only. This issue is the discussion point before any implementation PR, per the contributing guide.

Motivation

• The root AGENTS.md / monorepo layout already describe packages/svelte as the next integration after React.
• Svelte 5 apps cannot consume @appica/ui-react without a React runtime. A first-party port keeps one visual language across frameworks.
• Tokens, variants, and accessibility expectations should stay aligned with React so docs and Figma remain a single source of truth.

Proposed stack

Concern	React today	Svelte proposal
Framework	React 19	Svelte ^5.33 (runes only)
Headless primitives	Base UI (@base-ui/react)	Native HTML in Wave 1; bits-ui in Wave 2
Motion	Motion	CSS + svelte/transition (no Motion)
Styling	Tailwind v4 + CSS variables	Same tokens (var(--color-…), var(--radius-…), var(--transition-…))
Tests	vitest + Testing Library + vitest-axe	Same, with @testing-library/svelte
Playground	pnpm playground → playgrounds/react	pnpm playground:svelte → playgrounds/svelte

Do not add bits-ui until a component needs a headless primitive. Polymorphism is href / el (no public child snippet, no React render / cloneElement).

Scope

Port every public @appica/ui-react export (components, hooks, providers, color lib). Track progress in packages/svelte/COMPONENT-STATUS.md.

Wave 1 (native HTML): presentational primitives such as Alert, Avatar, Badge, ButtonGroup, Card, Input, Textarea, Table, Tabs chrome that does not need a primitive, ThemeProvider, and related hooks.

Wave 2 (bits-ui or custom): overlays and form controls that React wraps with Base UI: Accordion, Dialog, Select, Combobox, DateField / DatePicker / TimeField / Calendar, Menu family, Slider, Toast, and so on. Color controls and Carousel have no bits-ui analog and stay custom (Embla for Carousel, same plugins as React).

Svelte-specific API notes to keep in the port (not 1:1 React copies):

• $props() / $bindable() for fields; snippets (children, start, end) instead of slots.
• createContext / setContext instead of cloneElement.
• Overlay triggers take class={buttonVariants(...)} directly; links that look like a button use buttonVariants on <a>, not href on Button.
• Date values stay @internationalized/date DateValue / TimeValue, not native Date.
• src/index.ts and the package.json exports map are generated (pnpm --filter @appica/ui-svelte sync-exports).

Docs and contributing workflow

When the package lands, update the contributor-facing docs that today only mention React:

• CONTRIBUTING.md: Node floor (repo engines is >=22), pnpm --filter @appica/ui-svelte …, pnpm playground:svelte, playgrounds/svelte/src/app.svelte as the Svelte scratch page, and a packages/svelte layout paragraph pointing at packages/svelte/AGENTS.md.
• Root README.md: add @appica/ui-svelte to the package table once it is published.
• Root scripts: pack:svelte (and release if Svelte should publish with the same flow).

Docs site work (appica.dev /ui) lives in the separate appica-dev repo and is out of scope here, other than packing the tarball (pnpm pack:svelte) so that site can consume it.

Acceptance criteria

• packages/svelte publishes @appica/ui-svelte with the same component coverage as @appica/ui-react (checklist in COMPONENT-STATUS.md).
• Co-located tests pass: pnpm --filter @appica/ui-svelte test.
• pnpm --filter @appica/ui-svelte typecheck and build succeed; build emits .js + .d.ts (+ .svelte) for each public export.
• Vite playground at playgrounds/svelte hot-reloads against library source (pnpm playground:svelte).
• Theme via CSS variables only; shared tokens with React.
• CONTRIBUTING.md and root README document the Svelte package the same way they document React.
• Prop JSDoc follows the published API-reference rules (declared props only, @default when there is a default, American English, hyphen not a typographic dash).

Out of scope

• Vue / HTML packages.
• Changing the React public API to match Svelte.
• appica.dev docs pages (separate repo), aside from making the packed tarball consumable.

[rokaux]

Hey @triadmoko
Sorry for the wait.
Thanks for all the work you put into this. My colleague will check your PR and get back to you. We'll decide on further steps.