feat(ui): add Button, Modal, Spinner, Toast, and Tooltip components with styles

- Implemented Button component with various props for customization.
- Created Modal component with header, content, and footer subcomponents.
- Added Spinner component for loading indicators.
- Developed Toast component for displaying notifications.
- Introduced Tooltip component for contextual hints with keyboard shortcuts.
- Added corresponding CSS modules for styling each component.
- Updated index file to export new components.
- Configured TypeScript settings for the UI package.

packages/shared/src/hooks/useLogout.ts

@@ -0,0 +1,45 @@
+import { useCallback } from 'react';
+import { usePlatform } from '../platform';
+
+/**
+ * useLogout — wipes all client-side auth state and hard-reloads the
+ * app so AuthGuard lands on /login with a clean React tree (no stale
+ * Convex subscriptions, no lingering in-memory keys). Callers don't
+ * need to navigate themselves — the reload does it.
+ *
+ * Storage cleared (mirrors what AuthGuard hydrates on restore):
+ *   - localStorage: userId, username, publicKey, userPrefs_<userId>
+ *   - sessionStorage: privateKey, signingKey, masterKey, searchDbKey
+ *   - platform.session: full encrypted blob (Electron safeStorage / web localStorage)
+ */
+export function useLogout(): () => Promise<void> {
+	const { session } = usePlatform();
+
+	return useCallback(async () => {
+		try {
+			await session?.clear?.();
+		} catch (err) {
+			console.warn('Failed to clear platform session:', err);
+		}
+
+		try {
+			const userId = localStorage.getItem('userId');
+			localStorage.removeItem('userId');
+			localStorage.removeItem('username');
+			localStorage.removeItem('publicKey');
+			if (userId) localStorage.removeItem(`userPrefs_${userId}`);
+
+			sessionStorage.removeItem('privateKey');
+			sessionStorage.removeItem('signingKey');
+			sessionStorage.removeItem('masterKey');
+			sessionStorage.removeItem('searchDbKey');
+		} catch (err) {
+			console.warn('Failed to clear auth storage:', err);
+		}
+
+		// Hard reload: dumps the React tree, LiveKit rooms, Convex
+		// client, and any open audio/video contexts. AuthGuard then
+		// mounts fresh with empty storage and redirects to /login.
+		window.location.reload();
+	}, [session]);
+}