feat: 使用正确的 Gateway API - chat.send

关键修复:
- 之前错误：直接发送 message.inbound 事件
- 现在正确：使用 Gateway 的 chat.send 方法

Gateway API 调用:
{
  "type": "req",
  "method": "chat.send",
  "params": {
    "sessionKey": "wecom:group:chatId",
    "message": "文本内容",
    "attachments": [{"type": "image", "path": "..."}],
    "deliver": true,
    "idempotencyKey": "messageId"
  }
}

会话管理:
- sessionKey 格式：wecom:chatType:chatId
- 例如：wecom:group:123456789 或 wecom:direct:zhangsan
- OpenClaw 会自动创建或复用会话

媒体文件处理:
- 下载企业微信图片/文件
- 保存到本地媒体目录
- 通过 attachments 参数传递给 chat.send

这样才符合 OpenClaw Gateway 协议规范！

electron/main-chat-fix.js

@@ -0,0 +1,93 @@
+// 修复：使用正确的 Gateway API 发送消息
+
+// 转发消息到 OpenClaw - 使用 chat.send 方法
+async forwardMessageToOpenClaw(frame) {
+  if (!openclawConnection || !openclawConnection.isConnected) {
+    console.log('[WeCom] OpenClaw not connected, skipping forward');
+    return;
+  }
+
+  const body = frame.body;
+  const chatId = body.chatid || body.from.userid;
+  const chatType = body.chattype === 'group' ? 'group' : 'direct';
+  const messageId = body.msgid;
+  const reqId = frame.headers.req_id;
+
+  reqIdMap.set(chatId, reqId);
+
+  // 提取文本
+  let text = '';
+  if (body.text?.content) {
+    text = body.text.content;
+  } else if (body.mixed?.msg_item) {
+    for (const item of body.mixed.msg_item) {
+      if (item.msgtype === 'text' && item.text?.content) {
+        text += item.text.content + '\n';
+      }
+    }
+  } else if (body.voice?.content) {
+    text = body.voice.content;
+  }
+
+  if (body.chattype === 'group') {
+    text = text.replace(/@\S+/g, '').trim();
+  }
+
+  // 构建 sessionKey（格式：wecom:chatType:chatId）
+  const sessionKey = `wecom:${chatType}:${chatId}`;
+
+  // 处理媒体文件
+  const attachments = [];
+  
+  // 下载图片
+  if (body.image?.url) {
+    try {
+      console.log('[WeCom] Downloading image:', body.image.url);
+      const { buffer, filename } = await downloadFile(body.image.url, body.image.aeskey);
+      const saved = await saveMediaFile(buffer, filename, 'inbound');
+      attachments.push({
+        type: 'image',
+        path: saved.path,
+        contentType: saved.contentType
+      });
+      console.log('[WeCom] Image saved:', saved.path);
+    } catch (error) {
+      console.error('[WeCom] Failed to download image:', error.message);
+    }
+  }
+
+  // 下载文件
+  if (body.file?.url) {
+    try {
+      console.log('[WeCom] Downloading file:', body.file.url);
+      const { buffer, filename } = await downloadFile(body.file.url, body.file.aeskey);
+      const saved = await saveMediaFile(buffer, filename, 'inbound');
+      attachments.push({
+        type: 'file',
+        path: saved.path,
+        contentType: saved.contentType
+      });
+      console.log('[WeCom] File saved:', saved.path);
+    } catch (error) {
+      console.error('[WeCom] Failed to download file:', error.message);
+    }
+  }
+
+  // 使用 chat.send 方法发送消息到 OpenClaw
+  const chatSendMessage = {
+    type: 'req',
+    id: this.nextId(),
+    method: 'chat.send',
+    params: {
+      sessionKey: sessionKey,
+      message: text,
+      attachments: attachments.length > 0 ? attachments : undefined,
+      deliver: true,  // 立即投递到 AI
+      idempotencyKey: messageId  // 使用消息 ID 作为幂等键
+    }
+  };
+
+  console.log('[OpenClaw] Sending via chat.send:', sessionKey);
+  openclawConnection.send(JSON.stringify(chatSendMessage));
+  console.log(`[Forward] WeCom -> OpenClaw: ${messageId}`);
+}