fix: question controller fit with last vr

app/Http/Controllers/QuestionController.php

@@ -41,7 +41,48 @@ public function index(Request $request)
         });
     }
 
-        return response()->json($query->get());
+        return response()->json(
+            $query->get()->map(fn ($q) => $this->formatQuestion($q))->values()
+        );
+    }
+
+    /**
+     * Shape a question into the legacy (old Flutter) response: category_id and
+     * category are always present and non-null, tags is always an array, and
+     * timestamps are always ISO strings — so the old client never hits a null.
+     */
+    private function formatQuestion(Question $question): array
+    {
+        $question->loadMissing(['tags', 'category']);
+
+        $createdAt = optional($question->created_at)->toIso8601String();
+        $updatedAt = optional($question->updated_at)->toIso8601String();
+        $categoryId = $question->category_id ?? 0;
+
+        $category = $question->category;
+        $categoryPayload = $category
+            ? [
+                'id' => $category->id,
+                'name' => $category->name ?? '',
+                'created_at' => optional($category->created_at)->toIso8601String() ?? $createdAt,
+                'updated_at' => optional($category->updated_at)->toIso8601String() ?? $updatedAt,
+            ]
+            : [
+                'id' => $categoryId,
+                'name' => '',
+                'created_at' => $createdAt,
+                'updated_at' => $updatedAt,
+            ];
+
+        return [
+            'id' => $question->id,
+            'title' => $question->title ?? '',
+            'category_id' => $categoryId,
+            'created_at' => $createdAt,
+            'updated_at' => $updatedAt,
+            'tags' => $question->tags->values(),
+            'category' => $categoryPayload,
+        ];
     }
 
     /**
@@ -75,7 +116,7 @@ public function store(Request $request)
             $question->tags()->sync($tagIds);
         }
 
-        return response()->json($question->load(['tags', 'category']), 201);
+        return response()->json($this->formatQuestion($question), 201);
     }
 
     /**
@@ -83,7 +124,7 @@ public function store(Request $request)
      */
     public function show(Question $question)
     {
-        return response()->json($question->load(['tags', 'category']));
+        return response()->json($this->formatQuestion($question));
     }
 
     /**
@@ -120,7 +161,7 @@ public function update(Request $request, Question $question)
             $question->tags()->sync($tagIds);
         }
 
-        return response()->json($question->load(['tags', 'category']));
+        return response()->json($this->formatQuestion($question->fresh()));
     }
 
     /**