refactor: add return type hints to all controller methods

Added proper return types (View, RedirectResponse, JsonResponse, Collection)
to 40+ controller methods across 16 controllers. Also added missing
imports for Illuminate response types and tightened parameter types
(e.g. InstallationController::showStep now uses int instead of mixed).

app/Http/Controllers/Community/RadioLeaderboardController.php

@@ -9,10 +9,11 @@ use App\Models\User;
 use Carbon\Carbon;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\DB;
+use Illuminate\View\View;
 
 class RadioLeaderboardController extends Controller
 {
-    public function __invoke(Request $request)
+    public function __invoke(Request $request): View
     {
         $period = $request->get('period', 'all');