fix: address CodeRabbit review — a11y, test coverage, and Tailwind typo

- SignInPromptModal: add focus save/restore, Escape key handler, tabIndex
- SignInPromptModal.test.jsx: assert feature-specific copy in looped tests,
  add Escape/other-key tests (2 new tests, 1655 total)
- InsightFloatingActionButton: fix ring-off-2 → ring-offset-2 typo

Author: ayoub3bidi

src/components/InsightFloatingActionButton.jsx

@@ -69,7 +69,7 @@ export default function InsightFloatingActionButton({
           text-white rounded-full shadow-lg hover:shadow-xl
           items-center justify-center
           transition-all duration-200
-          focus:outline-none focus:ring-2 focus:ring-amber-400 focus:ring-off-2
+          focus:outline-none focus:ring-2 focus:ring-amber-400 focus:ring-offset-2
           touch-manipulation
         `}
         initial={{ scale: 0, opacity: 0 }}

src/components/SignInPromptModal.jsx

@@ -4,6 +4,7 @@
  * See LICENSE for details.
  */
 
+import { useEffect, useRef } from 'react';
 import { useTranslation } from 'react-i18next';
 import { GoogleLogo } from '@phosphor-icons/react';
 import { motion, AnimatePresence } from 'framer-motion';
@@ -13,20 +14,37 @@ function SignInPromptModal({ feature, isOpen, onClose }) {
   const { t } = useTranslation();
   const { signInWithGoogle } = useAuth();
   const featureLabel = t(`featureGate.${feature}`, { defaultValue: feature });
+  const dialogRef = useRef(null);
+
+  useEffect(() => {
+    if (!isOpen) return;
+
+    const prevFocus = document.activeElement;
+    dialogRef.current?.querySelector('button')?.focus();
+
+    return () => {
+      if (prevFocus && typeof prevFocus.focus === 'function') {
+        prevFocus.focus();
+      }
+    };
+  }, [isOpen]);
 
   return (
     <AnimatePresence>
       {isOpen && (
         <motion.div
+          ref={dialogRef}
           className="fixed inset-0 z-[100] flex items-center justify-center p-4 bg-black/60"
           initial={{ opacity: 0 }}
           animate={{ opacity: 1 }}
           exit={{ opacity: 0 }}
           transition={{ duration: 0.2 }}
           onClick={onClose}
+          onKeyDown={e => e.key === 'Escape' && onClose()}
           role="dialog"
           aria-modal="true"
           aria-label={t('featureGate.title', { feature: featureLabel })}
+          tabIndex={-1}
         >
           <motion.div
             className="bg-surface rounded-2xl shadow-2xl max-w-md w-full p-8"

src/components/SignInPromptModal.test.jsx

@@ -16,6 +16,14 @@ vi.mock('../hooks/useAuth', () => ({
 
 const FEATURES = ['code', 'insight', 'export', 'sound', 'fullscreen'];
 
+const FEATURE_LABELS = {
+  code: 'Code Panel',
+  insight: 'Algorithm Insight',
+  export: 'Video Export',
+  sound: 'Sound',
+  fullscreen: 'Fullscreen Mode',
+};
+
 describe('SignInPromptModal', () => {
   beforeEach(() => {
     signInWithGoogle.mockClear();
@@ -27,7 +35,11 @@ describe('SignInPromptModal', () => {
         <SignInPromptModal feature={featureKey} isOpen onClose={vi.fn()} />
       );
 
-      expect(screen.getByRole('dialog')).toBeInTheDocument();
+      const dialog = screen.getByRole('dialog');
+      expect(dialog).toBeInTheDocument();
+      expect(dialog).toHaveAccessibleName(
+        `Unlock ${FEATURE_LABELS[featureKey]}`
+      );
       expect(screen.getByText('Sign in with Google')).toBeInTheDocument();
       expect(screen.getByText('Maybe later')).toBeInTheDocument();
     });
@@ -70,4 +82,24 @@ describe('SignInPromptModal', () => {
     fireEvent.click(overlay);
     expect(onClose).toHaveBeenCalledTimes(1);
   });
+
+  it('closes on Escape key', () => {
+    const onClose = vi.fn();
+    renderWithI18n(
+      <SignInPromptModal feature="code" isOpen onClose={onClose} />
+    );
+
+    fireEvent.keyDown(screen.getByRole('dialog'), { key: 'Escape' });
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it('does not close on other keys', () => {
+    const onClose = vi.fn();
+    renderWithI18n(
+      <SignInPromptModal feature="code" isOpen onClose={onClose} />
+    );
+
+    fireEvent.keyDown(screen.getByRole('dialog'), { key: 'Enter' });
+    expect(onClose).not.toHaveBeenCalled();
+  });
 });