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/LeaderboardController.php

@@ -60,7 +60,7 @@ class LeaderboardController extends Controller
         ]);
     }
 
-    private function retrieveSettings($column)
+    private function retrieveSettings(string $column): \Illuminate\Database\Eloquent\Collection
     {
         return UserSetting::query()
             ->select(['user_id', $column])