feat: add auth guards and server-side logout with postcode search integration

- Add navigation guard requiring authentication for dashboard routes
- Create

routes/web.php

@@ -1,9 +1,20 @@
 <?php
 
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Auth;
 use Illuminate\Support\Facades\Route;
 
 // Named dashboard route so route('dashboard') resolves; Vue Router handles rendering
 Route::get('/dashboard', fn () => view('app'))->middleware(['auth', 'verified'])->name('dashboard');
 
+// Server-side logout — handles hard navigation to /logout
+Route::get('/logout', function (Request $request) {
+    Auth::logout();
+    $request->session()->invalidate();
+    $request->session()->regenerateToken();
+
+    return redirect('/');
+})->middleware('auth')->name('logout');
+
 // SPA catch-all — must be last
 Route::get('/{any?}', fn () => view('app'))->where('any', '.*')->name('home');