docs: update sidebar navigation documentation

Updated documentation to reflect new sidebar structure:
- Added Platform Administration section
- Added Customers page to navigation
- Updated page mapping table with all current pages
- Updated sidebar organization in page-templates.md
- Added customers logger to pre-configured loggers list

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

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

docs/frontend/admin/page-templates.md

@@ -1201,9 +1201,11 @@ cp app/static/admin/js/dashboard.js app/static/admin/js/new-page.js
 ### Pre-configured Loggers
 ```javascript
 window.LogConfig.loggers.dashboard
+window.LogConfig.loggers.companies
 window.LogConfig.loggers.vendors
 window.LogConfig.loggers.vendorTheme
 window.LogConfig.loggers.users
+window.LogConfig.loggers.customers
 window.LogConfig.loggers.products
 window.LogConfig.loggers.orders
 window.LogConfig.loggers.imports
@@ -1546,14 +1548,29 @@ async applyFilters() {
 ```javascript
 // Admin sidebar sections
 {
-    "Main Navigation": [
-        "Dashboard",
-        "Users",
+    "Dashboard": [
+        "Dashboard"
+    ],
+    "Platform Administration": [
+        "Companies",
         "Vendors",
-        "Marketplace Import"  // ← Self-service import
+        "Users",
+        "Customers",
+        "Marketplace"
+    ],
+    "Content Management": [
+        "Platform Homepage",
+        "Content Pages",
+        "Vendor Themes"
+    ],
+    "Developer Tools": [
+        "Components",
+        "Icons",
+        "Testing Hub",
+        "Code Quality"
     ],
     "Platform Monitoring": [
-        "Import Jobs",        // ← System-wide monitoring
+        "Import Jobs",
         "Application Logs"
     ],
     "Settings": [