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,
-                                    ),
-                                  ),
-                                ),
                               ],
                             ),
                           );
@@ -482,8 +471,33 @@ class AgentView extends StatelessWidget {
 
                     const SizedBox(width: 8),
 
-                    // 图片选择按钮
+                    // 动态按钮：图片选择按钮 或 发送按钮
-                    Container(
+                    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,
+                            ),
+                          ),
+                        );
+                      } else {
+                        // 显示图片选择按钮
+                        return Container(
                           width: 44,
                           height: 44,
                           decoration: BoxDecoration(
@@ -535,7 +549,9 @@ class AgentView extends StatelessWidget {
                               ),
                             ],
                           ),
-                    ),
+                        );
+                      }
+                    }),
                   ],
                 ),
               ],