修复：与AI聊天或其他特定错误拦截后，发送消息按钮永久失灵的问题

resources/views/chat/partials/scripts.blade.php

@@ -742,6 +742,7 @@
                 container2.appendChild(muteDiv);
                 container2.scrollTop = container2.scrollHeight;
             }
+            _isSending = false;
             return;
         }
 
@@ -753,6 +754,7 @@
         const content = formData.get('content').trim();
         if (!content) {
             contentInput.focus();
+            _isSending = false;
             return;
         }
 
@@ -762,6 +764,7 @@
             contentInput.value = '';
             contentInput.focus();
             await sendToChatBot(content);
+            _isSending = false;
             return;
         }