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/Auth/SocialAuthController.php

@@ -6,6 +6,7 @@ use App\Http\Controllers\Controller;
 use App\Models\SocialAccount;
 use App\Models\User;
 use Illuminate\Auth\Events\Registered;
+use Illuminate\Http\RedirectResponse;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Auth;
 use Illuminate\Support\Facades\Hash;
@@ -14,7 +15,7 @@ use Laravel\Socialite\Facades\Socialite;
 
 class SocialAuthController extends Controller
 {
-    public function redirect(string $provider)
+    public function redirect(string $provider): RedirectResponse
     {
         $enabled = $this->isProviderEnabled($provider);
 
@@ -26,7 +27,7 @@ class SocialAuthController extends Controller
         return Socialite::driver($provider)->redirect();
     }
 
-    public function callback(string $provider)
+    public function callback(string $provider): RedirectResponse
     {
         $enabled = $this->isProviderEnabled($provider);
 
@@ -124,12 +125,12 @@ class SocialAuthController extends Controller
         return $username;
     }
 
-    protected function redirectAfterLogin()
+    protected function redirectAfterLogin(): RedirectResponse
     {
         return redirect()->intended('/');
     }
 
-    public function unlink(Request $request, string $provider)
+    public function unlink(Request $request, string $provider): RedirectResponse
     {
         $user = $request->user();