feat: 通知发送层切换到群机器人 webhook, 排版精简

- wecom.py 重写: HTTP POST webhook(替代 aibot WebSocket 按需连接), 接口 send_markdown/send_text 不变, Secret Block wecom-webhook 存 URL
- webhook markdown 支持标题/引用/font 三色, 报告改为 '## 标题 + 单行结论 + 引用详情' 紧凑排版, 结论行用 info/warning 色
- alert_failure 改标题式排版; device_check 结论用 font 色, 去掉负载行
- 移除 wecom-aibot-sdk 依赖与 wecom_capture_chatid.py(镜像下次构建生效, 无需立即重建)

flows/monitor/alert_failure.py

@@ -102,14 +102,11 @@ def wecom_alert_failure(event: dict | str | None = None) -> dict:
             ended = detail.get("end_time") or detail.get("expected_start_time")
             occurred = occurred or ended
 
-        lines = [
-            f"🔴 **流程失败**  {flow_name or resource_name or '未知'}",
-        ]
-        if run_name and run_name != flow_name:
-            lines.append(f"> Run：{run_name}")
+        lines = [f"## 🔴 流程失败：{flow_name or resource_name or '未知'}"]
+        if run_name:
+            lines.append(f"> Run「{run_name}」 · {event_name.split('.')[-1]} · {_fmt_ts(occurred)}")
         if state_msg:
             lines.append(f"> 错误：{state_msg[:150].replace(chr(10), ' ')}")
-        lines.append(f"> {event_name} · {_fmt_ts(occurred)}")
         if run_id:
             lines.append(f"> [查看详情]({UI_BASE}/runs/flow-run/{run_id})")
         else: