Implement AuthGuard for route protection, integrate authorization checks into particles route, and simplify HeaderComponent access logic. Remove redundant debug logging in auth.service.ts.

frontend/src/app/app.routes.ts

@@ -1,4 +1,5 @@
 import {Routes} from '@angular/router';
+import {AuthGuard} from './guards/auth.guard';
 
 export const routes: Routes = [
   {
@@ -7,7 +8,11 @@ export const routes: Routes = [
   },
   {
     path: 'particles',
-    loadComponent: () => import('./pages/particles/particles.component').then(m => m.ParticlesComponent)
+    loadComponent: () => import('./pages/particles/particles.component').then(m => m.ParticlesComponent),
+    canActivate: [AuthGuard],
+    data: {
+      requiredAuthorizations: ['SCOPE_head_mod']
+    }
   },
   {
     path: 'map',