Add admin audit log viewer and system settings

Phase 5 (Admin Panel):
- Audit log viewer: searchable with action/date filters, expandable
  rows showing JSON changes, color-coded action chips, user avatars
- System settings: tabbed page (General, API Credentials, Billing,
  Notifications) with masked sensitive values, per-group save
- Settings model with get/set/getGroup/setGroup helpers
- Settings migration for key-value store with groups
- 52 tests passing, build clean

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

website/app/Http/Controllers/Admin/AuditLogController.php

@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers\Admin;
+
+use App\Http\Controllers\Controller;
+use App\Models\AuditLog;
+use Illuminate\Http\Request;
+use Inertia\Inertia;
+use Inertia\Response;
+
+class AuditLogController extends Controller
+{
+    public function index(Request $request): Response
+    {
+        $query = AuditLog::query()
+            ->with('user:id,name,email')
+            ->latest();
+
+        // Search by user name/email, action, or resource type
+        if ($search = $request->input('search')) {
+            $query->where(function ($q) use ($search): void {
+                $q->where('action', 'like', "%{$search}%")
+                    ->orWhere('resource_type', 'like', "%{$search}%")
+                    ->orWhere('ip_address', 'like', "%{$search}%")
+                    ->orWhereHas('user', function ($userQuery) use ($search): void {
+                        $userQuery->where('name', 'like', "%{$search}%")
+                            ->orWhere('email', 'like', "%{$search}%");
+                    });
+            });
+        }
+
+        // Filter by action
+        if ($action = $request->input('action')) {
+            $query->where('action', $action);
+        }
+
+        // Filter by date range
+        if ($dateFrom = $request->input('date_from')) {
+            $query->whereDate('created_at', '>=', $dateFrom);
+        }
+
+        if ($dateTo = $request->input('date_to')) {
+            $query->whereDate('created_at', '<=', $dateTo);
+        }
+
+        $auditLogs = $query->paginate(25)->withQueryString();
+
+        // Get distinct actions for the filter dropdown
+        $actions = AuditLog::query()
+            ->distinct()
+            ->orderBy('action')
+            ->pluck('action');
+
+        return Inertia::render('Admin/AuditLogs/Index', [
+            'auditLogs' => $auditLogs,
+            'actions' => $actions,
+            'filters' => [
+                'search' => $request->input('search', ''),
+                'action' => $request->input('action', ''),
+                'date_from' => $request->input('date_from', ''),
+                'date_to' => $request->input('date_to', ''),
+            ],
+        ]);
+    }
+}