feat: zero-knowledge recovery (Phase 2) — wrapped-DEK model

Introduces a wrapped-DEK recovery model so a forgotten password doesn't lose
all encrypted data. The encryption key becomes a random DEK (not derived from
the password); the DEK is wrapped under both a password-derived KEK and a
recovery-phrase-derived KEK, and both wrapped forms are stored on the server.

Crypto (crypto/keys.ts):
- DEK generation (random AES-256-GCM), KEK derivation (PBKDF2 password/recovery),
  wrapDek/unwrapDek/rewrapDek.
- setupEncryption(password, recoveryPhrase?) — generates a DEK, wraps under both
  KEKs, returns wrapped forms + recovery proof.
- unlockWithPassword(password, wrappedDek) — derives password KEK, unwraps DEK.
- unlockWithRecovery(phrase, wrappedDek) — derives recovery KEK, unwraps DEK.

Backend:
- User model: wrapped_dek, wrapped_dek_iv, recovery_wrapped_dek,
  recovery_wrapped_dek_iv fields.
- RegisterRequest accepts wrapped-DEK fields; stored verbatim.
- AuthResponse returns wrapped_dek + wrapped_dek_iv (for login unwrapping).
- New GET /api/auth/recovery-info?email= — returns recovery-wrapped DEK.
- RecoverPasswordRequest gains new_wrapped_dek + new_wrapped_dek_iv.
- change-password also accepts + stores re-wrapped DEK.

Frontend:
- Auth store: login unwraps DEK from response; new recover() action fetches
  recovery-wrapped DEK, unwraps with phrase, re-wraps under new password.
- RecoveryPage (new): email + recovery phrase + new password flow.
- LoginPage: 'Forgot password? Recover' link. App.tsx: /recover route.

Verified: backend 21 tests, 0 warnings; frontend build clean, 20 tests.

web/normogen-web/src/App.tsx

@@ -1,6 +1,7 @@
 import { BrowserRouter, Routes, Route, Navigate } from 'react-router-dom';
 import { LoginPage } from './pages/LoginPage';
 import { RegisterPage } from './pages/RegisterPage';
+import { RecoveryPage } from './pages/RecoveryPage';
 import { Dashboard } from './pages/Dashboard';
 import { ProtectedRoute } from './components/common/ProtectedRoute';
 
@@ -11,6 +12,7 @@ function App() {
         {/* Public routes */}
         <Route path="/login" element={<LoginPage />} />
         <Route path="/register" element={<RegisterPage />} />
+        <Route path="/recover" element={<RecoveryPage />} />
 
         {/* Protected routes */}
         <Route