feat(02-05): admin tab components and AdminView

- AdminView.vue: tabbed layout (Users | Quotas | AI Config) with UI-SPEC tab strip classes
- AdminUsersTab.vue: user table with create form (crypto.getRandomValues password), inline deactivation confirmation, reactivate, reset-password, row-level spinner, empty state
- AdminQuotasTab.vue: quota inline edit with MB display, usage %, warning when limit < usage
- AdminAiConfigTab.vue: AI provider/model per-user with 1.5s "Saved" confirmation
- client.js: fix adminDeactivateUser/adminReactivateUser to use PATCH /status endpoint, fix adminResetUserPassword to /password-reset, fix adminUpdateAiConfig to send ai_provider/ai_model, add adminGetUserQuota
- No impersonation UI in any admin component (T-02-31)

frontend/src/views/AdminView.vue

@@ -1,8 +1,8 @@
 <template>
-  <div class="p-8 max-w-4xl mx-auto">
-    <h2 class="text-2xl font-semibold text-gray-900 mb-4">Admin panel</h2>
+  <div class="p-8 max-w-5xl mx-auto">
+    <h2 class="text-2xl font-semibold text-gray-900 mb-6">Admin panel</h2>
 
-    <!-- Sub-navigation -->
+    <!-- Tab strip -->
     <div class="flex border-b border-gray-200 mb-6">
       <button
         v-for="tab in tabs"
@@ -17,17 +17,18 @@
       </button>
     </div>
 
-    <!-- Tab content (stub — wired in Phase 2 admin plan) -->
-    <div class="text-sm text-gray-500">
-      {{ activeTab === 'users' ? 'User management coming soon.' :
-         activeTab === 'quotas' ? 'Quota management coming soon.' :
-         'AI config management coming soon.' }}
-    </div>
+    <!-- Tab content -->
+    <AdminUsersTab v-if="activeTab === 'users'" />
+    <AdminQuotasTab v-if="activeTab === 'quotas'" />
+    <AdminAiConfigTab v-if="activeTab === 'ai'" />
   </div>
 </template>
 
 <script setup>
 import { ref } from 'vue'
+import AdminUsersTab from '../components/admin/AdminUsersTab.vue'
+import AdminQuotasTab from '../components/admin/AdminQuotasTab.vue'
+import AdminAiConfigTab from '../components/admin/AdminAiConfigTab.vue'
 
 const tabs = [
   { id: 'users', label: 'Users' },