feat: VM metrics via portal-monitor integration

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/Http/Middleware/AuthenticatePortalMonitor.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+
+class AuthenticatePortalMonitor
+{
+    public function handle(Request $request, Closure $next)
+    {
+        $expected = config('portal-monitor.config_api_key');
+        $provided = $request->header('X-Portal-Monitor-Key');
+
+        if (!is_string($expected)
+            || $expected === ''
+            || !is_string($provided)
+            || !hash_equals($expected, $provided)) {
+            return response()->json([
+                'error' => true,
+                'message' => 'Unauthorized',
+            ], 401);
+        }
+
+        return $next($request);
+    }
+}