优化代码结构，修复部分bug

lib/pages/movies/movie_review_form_page.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 import '../../providers/app_provider.dart';
 import '../../widgets/fade_in_local_image.dart';
+import 'package:uuid/uuid.dart';
 import '../../models/data_models.dart';
 import '../../utils/toast_util.dart';
 
@@ -307,7 +308,7 @@ class _MovieReviewFormPageState extends State<MovieReviewFormPage> {
 
     if (widget.review == null) {
       final newReview = MovieReview(
-        id: now.millisecondsSinceEpoch.toString(),
+        id: const Uuid().v4(),
         movieId: widget.movieId,
         content: _contentController.text.trim(),
         reviewer: _reviewerController.text.trim(),