feat: add master password hint functionality

- Updated user model to include masterPasswordHint.
- Modified sync handler to return masterPasswordHint.
- Implemented password hint retrieval in public API.
- Enhanced user profile management to allow updating of password hint.
- Added UI components for displaying and editing password hint.
- Updated localization files for new password hint strings.
- Improved rate limiting for sensitive public requests.
- Adjusted database schema to accommodate master password hint.

src/handlers/sync.ts

@@ -135,7 +135,7 @@ export async function handleSync(request: Request, env: Env, userId: string): Pr
     premium: true,
     premiumFromOrganization: false,
     usesKeyConnector: false,
-    masterPasswordHint: null,
+    masterPasswordHint: user.masterPasswordHint,
     culture: 'en-US',
     twoFactorEnabled: !!user.totpSecret,
     key: user.key,