fix: reduce long-poll timeout to 2s, make mark_as_seen async to unblock TG sender

src/summarizer.py

@@ -1,5 +1,6 @@
 import logging
 import re
+import threading
 from typing import Generator, Optional
 from src.config import Config
 from src.email_client import fetch_unseen_emails, mark_as_seen, Email
@@ -100,6 +101,11 @@ def tg_send_and_mark(cfg: Config, info: dict):
                      original_recipient=info.get("original_recipient", ""),
                      original_reply_to=info.get("original_reply_to", ""),
                      account_email=info.get("account_email", ""))
-    # 只有发送成功才标记已读
-    mark_as_seen(acct, [(info["uid"], info.get("folder", "INBOX"))])
-    logger.info(f"  TG 发送成功，已标记已读")
+    # 标记已读放到后台线程，不阻塞 TG 发送
+    def _bg_mark():
+        try:
+            mark_as_seen(acct, [(info["uid"], info.get("folder", "INBOX"))])
+        except Exception:
+            pass
+    threading.Thread(target=_bg_mark, daemon=True).start()
+    logger.info(f"  TG 发送成功，标记已读已提交后台")