feat: Implement TOTP-based two-factor authentication

- Added TOTP support for two-factor authentication in user profiles and login flows.
- Introduced device management endpoints to handle known devices and their registration.
- Enhanced database schema to include devices and trusted two-factor tokens.
- Updated response handling to include two-factor token in successful login responses.
- Modified registration and login pages to guide users through enabling TOTP.
- Improved device identification and management utilities for better user experience.

src/handlers/sync.ts

@@ -3,6 +3,7 @@ import { StorageService } from '../services/storage';
 import { errorResponse } from '../utils/response';
 import { cipherToResponse } from './ciphers';
 import { LIMITS } from '../config/limits';
+import { isTotpEnabled } from '../utils/totp';
 
 interface SyncCacheEntry {
   body: string;
@@ -73,7 +74,7 @@ export async function handleSync(request: Request, env: Env, userId: string): Pr
     usesKeyConnector: false,
     masterPasswordHint: null,
     culture: 'en-US',
-    twoFactorEnabled: false,
+    twoFactorEnabled: isTotpEnabled(env.TOTP_SECRET),
     key: user.key,
     privateKey: user.privateKey,
     accountKeys: null,