Update graduation workflow, promotions, and admin module improvements

app/Http/Controllers/GraduationBulkUploadController.php

@@ -3,6 +3,7 @@
 namespace App\Http\Controllers;
 
 use App\Models\StudentGraduation;
+use Illuminate\Http\JsonResponse;
 use Illuminate\Http\RedirectResponse;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\DB;
@@ -32,6 +33,27 @@ class GraduationBulkUploadController extends Controller
     }
 
     public function preview(Request $request): RedirectResponse
+    {
+        $preview = $this->buildPreviewPayload($request);
+
+        return $preview;
+    }
+
+    public function previewAjax(Request $request): JsonResponse
+    {
+        $preview = $this->buildPreviewPayload($request);
+
+        $request->session()->put('graduation_bulk_upload_preview', $preview);
+
+        return response()->json([
+            'success' => true,
+            'redirect_url' => route('graduated-students.bulk-upload.index'),
+            'summary' => $preview['summary'],
+            'message' => 'Preview bulk upload berhasil disiapkan.',
+        ]);
+    }
+
+    protected function buildPreviewPayload(Request $request): array
     {
         $validated = $request->validate([
             'document_type' => ['required', 'in:skl,ijazah,transcript,ukk-certificate,lsp-certificate'],
@@ -115,9 +137,7 @@ class GraduationBulkUploadController extends Controller
             'summary' => $summary,
         ];
 
-        $request->session()->put('graduation_bulk_upload_preview', $preview);
-
-        return redirect()->route('graduated-students.bulk-upload.index');
+        return $preview;
     }
 
     public function store(Request $request): RedirectResponse