feat(mfa): #64 WebAuthn complet — enregistrement/clé/verify login + gestion clés dans Sécurité (backend+frontend+i18n+tests)

frontend/locales/en.json

@@ -1581,7 +1581,6 @@
   "mfa.disable_confirm_btn": "Disable 2FA",
   "mfa.disabled_success": "2FA has been disabled.",
   "mfa.fill_all_fields": "Please fill in all fields.",
-
   "bookslm.title": "BooksLM",
   "bookslm.files_indexed": "{count} files indexed",
   "bookslm.chars_loaded": "{chars} chars loaded",
@@ -1601,5 +1600,18 @@
   "palette.bookslm_open": "BooksLM: Open for current directory",
   "palette.bookslm_new": "BooksLM: New conversation",
   "fab.open": "Open AI assistant",
-  "fab.close": "Close AI assistant"
+  "fab.close": "Close AI assistant",
+  "mfa.webauthn_title": "Security keys (WebAuthn)",
+  "mfa.webauthn_desc": "Authenticate with a physical key (YubiKey) or your device biometrics (Windows Hello, Touch ID).",
+  "mfa.webauthn_none": "No registered keys.",
+  "mfa.webauthn_add": "Add a security key",
+  "mfa.webauthn_label_prompt": "Key name (e.g. Pocket YubiKey)",
+  "mfa.webauthn_added": "Security key registered.",
+  "mfa.webauthn_removed": "Security key removed.",
+  "mfa.webauthn_remove": "Remove",
+  "mfa.webauthn_remove_confirm": "Enter your password to remove this key:",
+  "mfa.webauthn_prompt": "Present your security key or confirm with Windows Hello.",
+  "mfa.webauthn_btn": "Verify with my key",
+  "mfa.webauthn_cancelled": "WebAuthn ceremony cancelled.",
+  "mfa.webauthn_no_key": "No security key registered for this account."
 }