feat(消息通知): 添加对markdown格式消息的支持

新增send_markdown函数用于发送富文本格式消息，替换原有send_text调用以支持代码块、标题等格式内容显示。自动分割长消息为多个卡片发送，提升消息展示效果。

bot/feishu.py

@@ -108,6 +108,33 @@ async def send_text(receive_id: str, receive_id_type: str, text: str) -> None:
             await asyncio.sleep(0.3)
 
 
+async def send_markdown(receive_id: str, receive_id_type: str, content: str) -> None:
+    """
+    Send a markdown card message. Used for LLM/agent replies that contain
+    formatted text (code blocks, headings, bold, lists, etc.).
+
+    Automatically splits long content into multiple cards.
+    """
+    parts = _split_message(content)
+
+    for i, part in enumerate(parts):
+        card = {
+            "schema": "2.0",
+            "body": {
+                "elements": [
+                    {
+                        "tag": "markdown",
+                        "content": part,
+                    }
+                ]
+            }
+        }
+        await send_card(receive_id, receive_id_type, card)
+
+        if len(parts) > 1 and i < len(parts) - 1:
+            await asyncio.sleep(0.3)
+
+
 async def send_card(receive_id: str, receive_id_type: str, card: dict) -> None:
     """
     Send an interactive card message.

bot/handler.py

@@ -13,7 +13,7 @@ import lark_oapi as lark
 from lark_oapi.api.im.v1 import P2ImMessageReceiveV1
 
 from bot.commands import handle_command
-from bot.feishu import send_text
+from bot.feishu import send_text, send_markdown
 from config import FEISHU_APP_ID, FEISHU_APP_SECRET, is_user_allowed
 from orchestrator.agent import agent
 from orchestrator.tools import set_current_chat
@@ -177,14 +177,14 @@ async def _process_message(user_id: str, chat_id: str, text: str) -> None:
             try:
                 reply = await forward(node_id, user_id, chat_id, text)
                 if reply:
-                    await send_text(chat_id, "chat_id", reply)
+                    await send_markdown(chat_id, "chat_id", reply)
             except Exception as e:
                 logger.exception("Failed to forward to node %s", node_id)
                 await send_text(chat_id, "chat_id", f"Error communicating with node: {e}")
         else:
             reply = await agent.run(user_id, text)
             if reply:
-                await send_text(chat_id, "chat_id", reply)
+                await send_markdown(chat_id, "chat_id", reply)
     except Exception:
         logger.exception("Error processing message for user %s", user_id)