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>

nuxt.config.ts

@@ -41,7 +41,7 @@ export default defineNuxtConfig({
       || process.env.NUXT_PUBLIC_API_BASE_URL
       || 'http://localhost/api',
     public: {
-      apiBaseUrl: process.env.NUXT_PUBLIC_API_BASE_URL || 'http://localhost:8081/api',
+      apiBaseUrl: process.env.NUXT_PUBLIC_API_BASE_URL || '/api',
       appUrl: process.env.NUXT_PUBLIC_APP_URL || 'http://localhost:3001',
       appName: process.env.NUXT_PUBLIC_APP_NAME || 'Inventory Management System',
       appVersion: appVersion,
@@ -54,7 +54,15 @@ export default defineNuxtConfig({
     }
   },
   vite: {
-    plugins: [tailwindcss()]
+    plugins: [tailwindcss()],
+    server: {
+      proxy: {
+        '/api': {
+          target: 'http://localhost',
+          changeOrigin: true,
+        },
+      },
+    },
   },
   css: ['~/assets/app.css'],
   router: {