feat(agent): 添加动态发送按钮显示逻辑

在输入框有内容时显示发送按钮，否则显示图片选择按钮

lib/modules/agent/controllers/agent_controller.dart

@@ -68,6 +68,9 @@ class AgentController extends GetxController {
   final isImageInputActive = false.obs; // 是否处于图片输入模式
   final selectedImagePath = Rx<String?>(null); // 当前选择的图片路径
 
+  // 输入状态控制 - 用于动态显示发送按钮
+  final hasTextInput = false.obs; // 是否有文本输入
+
   // 流事件订阅
   StreamSubscription<AgentServiceEvent>? _eventSubscription;
 
@@ -107,6 +110,7 @@ class AgentController extends GetxController {
     _subscribeToEvents(); //订阅代理服务事件
     _initMusicStatus(); //初始化音乐状态
     _setupMediaSessionCallbacks(); //设置媒体会话回调
+    _setupTextInputListener(); //设置文本输入监听器
   }
 
   // 初始化音乐播放状态
@@ -178,6 +182,14 @@ class AgentController extends GetxController {
     }
   }
 
+  // 设置文本输入监听器
+  void _setupTextInputListener() {
+    textController.addListener(() {
+      final text = textController.text.trim();
+      hasTextInput.value = text.isNotEmpty;
+    });
+  }
+
   // 加载聊天历史记录
   Future<void> _loadChatHistory() async {
     try {

lib/modules/agent/views/agent_view.dart

@@ -390,17 +390,6 @@ class AgentView extends StatelessWidget {
                                     );
                                   }),
                                 ),
-                                GestureDetector(
-                                  onTap: () => controller.sendMessage(),
-                                  child: Container(
-                                    padding: const EdgeInsets.all(6),
-                                    child: Icon(
-                                      Icons.send,
-                                      color: primaryColor,
-                                      size: 22,
-                                    ),
-                                  ),
-                                ),
                               ],
                             ),
                           );
@@ -482,60 +471,87 @@ class AgentView extends StatelessWidget {
 
                     const SizedBox(width: 8),
 
-                    // 图片选择按钮
-                    Container(
-                      width: 44,
-                      height: 44,
-                      decoration: BoxDecoration(
-                        color: isDarkMode ? Colors.grey[800] : Colors.grey[200],
-                        borderRadius: BorderRadius.circular(22),
-                      ),
-                      child: PopupMenuButton<String>(
-                        icon: Icon(
-                          Icons.add_photo_alternate_outlined,
-                          color:
-                              isDarkMode ? Colors.grey[300] : Colors.grey[700],
-                          size: 22,
-                        ),
-                        padding: EdgeInsets.zero,
-                        shape: RoundedRectangleBorder(
-                          borderRadius: BorderRadius.circular(12),
-                        ),
-                        onSelected: (value) async {
-                          if (value == 'camera') {
-                            await controller.takePhoto();
-                          } else if (value == 'gallery') {
-                            await controller.pickImage();
-                          }
-                        },
-                        itemBuilder: (context) => [
-                          PopupMenuItem<String>(
-                            value: 'camera',
-                            child: Row(
-                              children: [
-                                Icon(Icons.camera_alt,
-                                    color: primaryColor, size: 20),
-                                const SizedBox(width: 8),
-                                const Text('拍照',
-                                    style: TextStyle(fontSize: 14)),
-                              ],
+                    // 动态按钮：图片选择按钮 或 发送按钮
+                    Obx(() {
+                      final hasText = controller.hasTextInput.value;
+                      final hasImage = controller.isImageInputActive.value;
+                      final shouldShowSend = hasText || hasImage;
+
+                      if (shouldShowSend) {
+                        // 显示发送按钮
+                        return GestureDetector(
+                          onTap: () => controller.sendMessage(),
+                          child: Container(
+                            width: 44,
+                            height: 44,
+                            decoration: BoxDecoration(
+                              color: primaryColor,
+                              borderRadius: BorderRadius.circular(22),
+                            ),
+                            child: const Icon(
+                              Icons.send,
+                              color: Colors.white,
+                              size: 22,
                             ),
                           ),
-                          PopupMenuItem<String>(
-                            value: 'gallery',
-                            child: Row(
-                              children: [
-                                Icon(Icons.photo_library,
-                                    color: primaryColor, size: 20),
-                                const SizedBox(width: 8),
-                                const Text('从相册选择',
-                                    style: TextStyle(fontSize: 14)),
-                              ],
+                        );
+                      } else {
+                        // 显示图片选择按钮
+                        return Container(
+                          width: 44,
+                          height: 44,
+                          decoration: BoxDecoration(
+                            color: isDarkMode ? Colors.grey[800] : Colors.grey[200],
+                            borderRadius: BorderRadius.circular(22),
+                          ),
+                          child: PopupMenuButton<String>(
+                            icon: Icon(
+                              Icons.add_photo_alternate_outlined,
+                              color:
+                                  isDarkMode ? Colors.grey[300] : Colors.grey[700],
+                              size: 22,
                             ),
+                            padding: EdgeInsets.zero,
+                            shape: RoundedRectangleBorder(
+                              borderRadius: BorderRadius.circular(12),
+                            ),
+                            onSelected: (value) async {
+                              if (value == 'camera') {
+                                await controller.takePhoto();
+                              } else if (value == 'gallery') {
+                                await controller.pickImage();
+                              }
+                            },
+                            itemBuilder: (context) => [
+                              PopupMenuItem<String>(
+                                value: 'camera',
+                                child: Row(
+                                  children: [
+                                    Icon(Icons.camera_alt,
+                                        color: primaryColor, size: 20),
+                                    const SizedBox(width: 8),
+                                    const Text('拍照',
+                                        style: TextStyle(fontSize: 14)),
+                                  ],
+                                ),
+                              ),
+                              PopupMenuItem<String>(
+                                value: 'gallery',
+                                child: Row(
+                                  children: [
+                                    Icon(Icons.photo_library,
+                                        color: primaryColor, size: 20),
+                                    const SizedBox(width: 8),
+                                    const Text('从相册选择',
+                                        style: TextStyle(fontSize: 14)),
+                                  ],
+                                ),
+                              ),
+                            ],
                           ),
-                        ],
-                      ),
-                    ),
+                        );
+                      }
+                    }),
                   ],
                 ),
               ],