feat: billing/invoice details (full name, address, phone) under Settings > Billing (v0.76.0)

Adds a new user_billing_details table (1:1 with users, separate from the display name) with a form and GET/PUT API route. Full name is required by the form/API; address and phone stay optional. Not wired into Stripe invoicing yet — just captured for future use.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/messages/en.json

@@ -1600,6 +1600,18 @@
     "modelDefault": "Default",
     "modelSaving": "Saving…",
     "saveModelPrefs": "Save model preferences",
+    "billingFullName": "Full name",
+    "billingFullNameRequired": "Full name is required",
+    "billingAddressLine1": "Address line 1",
+    "billingAddressLine2": "Address line 2",
+    "billingCity": "City",
+    "billingPostalCode": "Postal code",
+    "billingCountry": "Country",
+    "billingPhone": "Phone number",
+    "billingDetailsSaved": "Billing details saved",
+    "billingDetailsSaveFailed": "Failed to save billing details",
+    "billingDetailsSaving": "Saving…",
+    "saveBillingDetails": "Save billing details",
     "userUpdated": "User updated successfully",
     "userUpdateFailed": "Failed to save",
     "adminSettingsSaved": "Settings saved",

apps/web/messages/fr.json

@@ -1591,6 +1591,18 @@
     "saveModelPrefs": "Enregistrer les préférences de modèle",
     "modelDefaultPlaceholder": "Par défaut",
     "modelNamePlaceholder": "ex. llama3.2",
+    "billingFullName": "Nom complet",
+    "billingFullNameRequired": "Le nom complet est obligatoire",
+    "billingAddressLine1": "Adresse (ligne 1)",
+    "billingAddressLine2": "Adresse (ligne 2)",
+    "billingCity": "Ville",
+    "billingPostalCode": "Code postal",
+    "billingCountry": "Pays",
+    "billingPhone": "Numéro de téléphone",
+    "billingDetailsSaved": "Coordonnées de facturation enregistrées",
+    "billingDetailsSaveFailed": "Échec de l'enregistrement des coordonnées de facturation",
+    "billingDetailsSaving": "Enregistrement…",
+    "saveBillingDetails": "Enregistrer les coordonnées",
     "userUpdated": "Utilisateur mis à jour avec succès",
     "userUpdateFailed": "Échec de l'enregistrement",
     "adminSettingsSaved": "Paramètres enregistrés",