feat: redesign auth pages — rounded-[48px] cards, serif titles, orbs, icon inputs

- Auth layout: warm background with brand-accent/ochre orbs, header with Globe + Momento branding
- Login form: serif heading, icon-inputs with focus transitions, uppercase labels, submit with arrow
- Register form: matching card style with User/Mail/Lock icons, confirm password field
- Forgot password: matching card with email icon, success state with mail icon
- Reset password: matching card with Lock icons, invalid link state with AlertCircle
- All text via i18n (new keys: welcomeBack, createYourSpace, forgot, etc.)
- Dark mode support via CSS variables
- Removed shadcn Card/Button/Input dependencies from auth forms

memento-note/locales/fr.json

@@ -28,7 +28,14 @@
     "backToLogin": "Retour à la connexion",
     "signOut": "Déconnexion",
     "confirmPassword": "Confirmer le mot de passe",
-    "confirmPasswordPlaceholder": "Confirmez votre mot de passe"
+    "confirmPasswordPlaceholder": "Confirmez votre mot de passe",
+    "welcomeBack": "Bon retour parmi nous",
+    "welcomeBackSubtitle": "Entrez vos identifiants pour accéder à vos notes.",
+    "createYourSpace": "Créer votre espace",
+    "createYourSpaceSubtitle": "Rejoignez la nouvelle ère de la prise de notes intelligente.",
+    "forgot": "Oublié ?",
+    "backToSite": "Retour",
+    "privacyTerms": "© 2025 Momento Labs — Confidentialité · Conditions"
   },
   "sidebar": {
     "notes": "Notes",