feat(permissions) : add role-based UI guards and readonly mode for viewers

- Add usePermissions composable (isAdmin, canEdit, canView)
- Password-protected profile login with modal on profiles page
- Disable all form fields for ROLE_VIEWER across edit/create pages
- Show navigation buttons (Modifier/Consulter) for all roles, hide delete for viewers
- Add readonly prop to ModelTypeForm for category pages
- Disable modal fields (sites, constructeurs) for viewers
- Guard /admin routes in middleware

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/components/sites/SiteContactFormFields.vue

@@ -9,11 +9,12 @@
         type="text"
         placeholder="Nom et prénom"
         class="input input-bordered"
+        :disabled="disabled"
         required
       />
     </div>
 
-    <FieldPhone v-model="contactPhone" required />
+    <FieldPhone v-model="contactPhone" :disabled="disabled" required />
 
     <div class="form-control">
       <label class="label">
@@ -24,6 +25,7 @@
         type="text"
         placeholder="Adresse complète"
         class="input input-bordered"
+        :disabled="disabled"
         required
       />
     </div>
@@ -38,6 +40,7 @@
           type="text"
           placeholder="Code postal"
           class="input input-bordered"
+          :disabled="disabled"
           required
         />
       </div>
@@ -51,6 +54,7 @@
           type="text"
           placeholder="Ville"
           class="input input-bordered"
+          :disabled="disabled"
           required
         />
       </div>
@@ -77,6 +81,10 @@ const props = defineProps({
     type: Object as PropType<SiteForm>,
     required: true,
   },
+  disabled: {
+    type: Boolean,
+    default: false,
+  },
 })
 
 const form = toRef(props, 'form')