refactor(09-05): CODE-09 purge — Phase 9 files (WHAT comments removed)

Frontend: AdminLayout, AdminSidebar, AdminOverviewView, AdminUsersView,
AdminQuotasView, AdminAiView, AdminAuditView, router/index.js, LoginView,
tailwind.config.js, api/admin.js — WHAT labels stripped; WHY constraints
preserved (D-16 anchors, security notes, api_key write-only invariant,
router guard rationale, D-08/D-09/D-10 decision refs, fetchWithRetry reason).
Backend: overview.py was already clean (no WHAT comments present).
Frontend: 137 tests pass, build succeeds.

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

frontend/src/components/admin/AdminSidebar.vue

@@ -1,14 +1,11 @@
 <template>
   <aside class="w-64 bg-white border-r border-gray-200 flex flex-col h-full shrink-0">
-    <!-- Logo -->
     <div class="px-6 py-5 border-b border-gray-100">
       <h1 class="text-lg font-bold text-indigo-600 tracking-tight">DocuVault</h1>
       <p class="text-xs text-indigo-500 font-semibold mt-0.5">Admin</p>
     </div>
 
-    <!-- Nav -->
     <nav class="flex-1 px-3 py-4 overflow-y-auto">
-      <!-- Overview -->
       <router-link
         to="/admin"
         class="nav-link"
@@ -21,7 +18,6 @@
         Overview
       </router-link>
 
-      <!-- Users -->
       <router-link
         to="/admin/users"
         class="nav-link"
@@ -34,7 +30,6 @@
         Users
       </router-link>
 
-      <!-- Quotas -->
       <router-link
         to="/admin/quotas"
         class="nav-link"
@@ -47,7 +42,6 @@
         Quotas
       </router-link>
 
-      <!-- AI Config -->
       <router-link
         to="/admin/ai"
         class="nav-link"
@@ -60,7 +54,6 @@
         AI Config
       </router-link>
 
-      <!-- Audit Log -->
       <router-link
         to="/admin/audit"
         class="nav-link"
@@ -74,7 +67,6 @@
       </router-link>
     </nav>
 
-    <!-- User identity footer -->
     <div class="px-3 py-4 border-t border-gray-100">
       <div v-if="authStore.user" class="flex items-center gap-3 px-4 py-3 border-t border-gray-100 mt-2 -mx-3">
         <div class="bg-indigo-100 text-indigo-700 text-xs font-semibold rounded-full w-8 h-8 flex items-center justify-center shrink-0">