feat(message): 实现聊天页面消息分页加载功能

- 将 ChatPage 从 StatelessWidget 改为 StatefulWidget
- 添加 ScrollController 监听列表滚动
- 实现滚动到底部时自动加载更多消息- 新增 _loadMoreMessages 方法处理分页逻辑
- 在控制器中调用 fetchMessages 方法加载历史消息- 添加加载状态防止重复请求
- 优化 dispose 方法释放滚动控制器资源

lib/pages/message/chat_page.dart

@@ -10,15 +10,48 @@ import '../../generated/assets.dart';
 import '../../../widget/message/chat_input_bar.dart';
 import '../../../widget/message/message_item.dart';
 
-class ChatPage extends StatelessWidget {
+class ChatPage extends StatefulWidget {
   final String userId;
 
   const ChatPage({required this.userId, super.key});
 
+  @override
+  State<ChatPage> createState() => _ChatPageState();
+}
+
+class _ChatPageState extends State<ChatPage> {
+  final ScrollController _scrollController = ScrollController();
+  bool _isLoadingMore = false;
+  late ChatController _controller;
+
+  @override
+  void initState() {
+    super.initState();
+    // 初始化 controller
+    _controller = Get.put(ChatController(userId: widget.userId));
+
+    // 监听滚动，当滚动到顶部时加载更多消息
+    _scrollController.addListener(() {
+      if (_scrollController.hasClients &&
+          _scrollController.position.pixels >=
+              _scrollController.position.maxScrollExtent - 100 &&
+          !_isLoadingMore &&
+          _controller.messages.isNotEmpty) {
+        _loadMoreMessages();
+      }
+    });
+  }
+
+  @override
+  void dispose() {
+    _scrollController.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     return GetBuilder<ChatController>(
-      init: ChatController(userId: userId),
+      init: _controller,
       builder: (controller) {
         return WillPopScope(
           onWillPop: () async {
@@ -57,6 +90,7 @@ class ChatPage extends StatelessWidget {
                       },
                       behavior: HitTestBehavior.opaque,
                       child: ListView.builder(
+                        controller: _scrollController,
                         reverse: true,
                         padding: EdgeInsets.all(16.w),
                         itemCount: controller.messages.length,
@@ -79,34 +113,53 @@ class ChatPage extends StatelessWidget {
                     ),
                   ),
                 ),
-              // 使用抽离的聊天输入栏组件
-              ChatInputBar(
-                onSendMessage: (message) async {
-                  await controller.sendMessage(message);
-                },
-                onImageSelected: (imagePaths) async {
-                  // 为每个图片路径调用控制器的方法发送图片消息
-                  for (var imagePath in imagePaths) {
-                    await controller.sendImageMessage(imagePath);
-                  }
-                },
-                onVoiceRecorded: (filePath, seconds) async {
-                  // 处理语音录音完成，回传文件路径和秒数
-                  await controller.sendVoiceMessage(filePath, seconds);
-                },
-                onVideoRecorded: (filePath, duration) async {
-                  print('🎬 [ChatPage] 收到视频录制/选择回调');
-                  print('文件路径: $filePath');
-                  print('时长: $duration 秒');
-                  // 处理视频录制/选择完成，回传文件路径和时长
-                  await controller.sendVideoMessage(filePath, duration);
-                },
-              ),
-            ],
+                // 使用抽离的聊天输入栏组件
+                ChatInputBar(
+                  onSendMessage: (message) async {
+                    await controller.sendMessage(message);
+                  },
+                  onImageSelected: (imagePaths) async {
+                    // 为每个图片路径调用控制器的方法发送图片消息
+                    for (var imagePath in imagePaths) {
+                      await controller.sendImageMessage(imagePath);
+                    }
+                  },
+                  onVoiceRecorded: (filePath, seconds) async {
+                    // 处理语音录音完成，回传文件路径和秒数
+                    await controller.sendVoiceMessage(filePath, seconds);
+                  },
+                  onVideoRecorded: (filePath, duration) async {
+                    print('🎬 [ChatPage] 收到视频录制/选择回调');
+                    print('文件路径: $filePath');
+                    print('时长: $duration 秒');
+                    // 处理视频录制/选择完成，回传文件路径和时长
+                    await controller.sendVideoMessage(filePath, duration);
+                  },
+                ),
+              ],
+            ),
           ),
-        ),
-      );
+        );
       },
     );
   }
+
+  // 加载更多消息
+  Future<void> _loadMoreMessages() async {
+    if (_isLoadingMore) return;
+
+    setState(() {
+      _isLoadingMore = true;
+    });
+
+    try {
+      await _controller.fetchMessages(loadMore: true);
+    } finally {
+      if (mounted) {
+        setState(() {
+          _isLoadingMore = false;
+        });
+      }
+    }
+  }
 }