feat(admin): add Platform Administration section to sidebar

Reorganized sidebar navigation:
- Added "Platform Administration" section header below Dashboard
- Grouped Companies, Vendors, Users, Customers, Marketplace under it
- Added new Customers page (empty placeholder for future)
- Changed Marketplace icon from shopping-bag to globe
- Renamed "Marketplace Import" to "Marketplace" for brevity

New files:
- app/templates/admin/customers.html
- Route: GET /admin/customers

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/routes/admin_pages.py

@@ -23,6 +23,7 @@ Routes:
 - GET /vendor-themes → Vendor themes selection page (auth required)
 - GET /vendors/{vendor_code}/theme → Vendor theme editor (auth required)
 - GET /users         → User management page (auth required)
+- GET /customers     → Customer management page (auth required)
 - GET /imports       → Import history page (auth required)
 - GET /settings      → Settings page (auth required)
 - GET /platform-homepage → Platform homepage manager (auth required)
@@ -449,6 +450,30 @@ async def admin_user_edit_page(
     )
 
 
+# ============================================================================
+# CUSTOMER MANAGEMENT ROUTES
+# ============================================================================
+
+
+@router.get("/customers", response_class=HTMLResponse, include_in_schema=False)
+async def admin_customers_page(
+    request: Request,
+    current_user: User = Depends(get_current_admin_from_cookie_or_header),
+    db: Session = Depends(get_db),
+):
+    """
+    Render customers management page.
+    Shows list of all platform customers.
+    """
+    return templates.TemplateResponse(
+        "admin/customers.html",
+        {
+            "request": request,
+            "user": current_user,
+        },
+    )
+
+
 # ============================================================================
 # IMPORT MANAGEMENT ROUTES
 # ============================================================================

app/templates/admin/customers.html

@@ -0,0 +1,51 @@
+{# app/templates/admin/customers.html #}
+{% extends "admin/base.html" %}
+
+{% block title %}Customers{% endblock %}
+
+{% block alpine_data %}adminCustomers(){% endblock %}
+
+{% block content %}
+<!-- Page Header -->
+<div class="flex items-center justify-between my-6">
+    <div>
+        <h2 class="text-2xl font-semibold text-gray-700 dark:text-gray-200">
+            Customers
+        </h2>
+        <p class="text-sm text-gray-600 dark:text-gray-400 mt-1">
+            Manage platform customers
+        </p>
+    </div>
+</div>
+
+<!-- Empty State -->
+<div class="px-4 py-12 bg-white rounded-lg shadow-md dark:bg-gray-800">
+    <div class="text-center">
+        <span x-html="$icon('user-group', 'mx-auto h-12 w-12 text-gray-400')"></span>
+        <h3 class="mt-4 text-lg font-medium text-gray-900 dark:text-gray-100">
+            Customers Management
+        </h3>
+        <p class="mt-2 text-sm text-gray-500 dark:text-gray-400">
+            Customer management features coming soon.
+        </p>
+        <p class="mt-1 text-sm text-gray-500 dark:text-gray-400">
+            This section will allow you to view and manage customers across all vendors.
+        </p>
+    </div>
+</div>
+{% endblock %}
+
+{% block extra_scripts %}
+<script>
+function adminCustomers() {
+    return {
+        ...data(),
+        currentPage: 'customers',
+
+        init() {
+            console.log('Customers page initialized');
+        }
+    };
+}
+</script>
+{% endblock %}

app/templates/admin/partials/sidebar.html

@@ -18,8 +18,14 @@
             </li>
         </ul>
 
-        <!-- Main Navigation -->
+        <!-- Platform Administration Section -->
-        <ul>
+        <div class="px-6 my-6">
+            <hr class="border-gray-200 dark:border-gray-700" />
+        </div>
+        <p class="px-6 text-xs font-semibold text-gray-600 dark:text-gray-400 uppercase tracking-wider">
+            Platform Administration
+        </p>
+        <ul class="mt-3">
             <!-- Companies -->
             <li class="relative px-6 py-3">
                 <span x-show="currentPage === 'companies'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
@@ -53,14 +59,25 @@
                 </a>
             </li>
 
-            <!-- Marketplace Import -->
+            <!-- Customers -->
+            <li class="relative px-6 py-3">
+                <span x-show="currentPage === 'customers'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
+                <a class="inline-flex items-center w-full text-sm font-semibold transition-colors duration-150 hover:text-gray-800 dark:hover:text-gray-200"
+                   :class="currentPage === 'customers' ? 'text-gray-800 dark:text-gray-100' : ''"
+                   href="/admin/customers">
+                    <span x-html="$icon('user-group')"></span>
+                    <span class="ml-4">Customers</span>
+                </a>
+            </li>
+
+            <!-- Marketplace -->
             <li class="relative px-6 py-3">
                 <span x-show="currentPage === 'marketplace'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
                 <a class="inline-flex items-center w-full text-sm font-semibold transition-colors duration-150 hover:text-gray-800 dark:hover:text-gray-200"
                    :class="currentPage === 'marketplace' ? 'text-gray-800 dark:text-gray-100' : ''"
                    href="/admin/marketplace">
-                    <span x-html="$icon('shopping-bag')"></span>
+                    <span x-html="$icon('globe')"></span>
-                    <span class="ml-4">Marketplace Import</span>
+                    <span class="ml-4">Marketplace</span>
                 </a>
             </li>
         </ul>
@@ -247,8 +264,14 @@
             </li>
         </ul>
 
-        <!-- Main Navigation -->
+        <!-- Platform Administration Section -->
-        <ul>
+        <div class="px-6 my-6">
+            <hr class="border-gray-200 dark:border-gray-700" />
+        </div>
+        <p class="px-6 text-xs font-semibold text-gray-600 dark:text-gray-400 uppercase tracking-wider">
+            Platform Administration
+        </p>
+        <ul class="mt-3">
             <!-- Companies -->
             <li class="relative px-6 py-3">
                 <span x-show="currentPage === 'companies'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
@@ -282,14 +305,25 @@
                 </a>
             </li>
 
-            <!-- Marketplace Import -->
+            <!-- Customers -->
+            <li class="relative px-6 py-3">
+                <span x-show="currentPage === 'customers'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
+                <a class="inline-flex items-center w-full text-sm font-semibold transition-colors duration-150 hover:text-gray-800 dark:hover:text-gray-200"
+                   :class="currentPage === 'customers' ? 'text-gray-800 dark:text-gray-100' : ''"
+                   href="/admin/customers">
+                    <span x-html="$icon('user-group')"></span>
+                    <span class="ml-4">Customers</span>
+                </a>
+            </li>
+
+            <!-- Marketplace -->
             <li class="relative px-6 py-3">
                 <span x-show="currentPage === 'marketplace'" class="absolute inset-y-0 left-0 w-1 bg-purple-600 rounded-tr-lg rounded-br-lg" aria-hidden="true"></span>
                 <a class="inline-flex items-center w-full text-sm font-semibold transition-colors duration-150 hover:text-gray-800 dark:hover:text-gray-200"
                    :class="currentPage === 'marketplace' ? 'text-gray-800 dark:text-gray-100' : ''"
                    href="/admin/marketplace">
-                    <span x-html="$icon('shopping-bag')"></span>
+                    <span x-html="$icon('globe')"></span>
-                    <span class="ml-4">Marketplace Import</span>
+                    <span class="ml-4">Marketplace</span>
                 </a>
             </li>
         </ul>