fix: remove body truncation for large emails

src/email_client.py

@@ -116,7 +116,20 @@ def fetch_unseen_emails(account: EmailAccount) -> list[Email]:
 
     for uid in uids:
         try:
-            _, msg_data = conn.uid("FETCH", uid, "RFC822")
+            # 先查大小，大邮件用 PEEK 避免长时间阻塞导致连接断开被标已读
+            _, size_data = conn.uid("FETCH", uid, "(RFC822.SIZE)")
+            size = 0
+            if size_data[0]:
+                m = re.search(rb"RFC822\.SIZE (\d+)", size_data[0])
+                if m:
+                    size = int(m.group(1))
+            large = size > 200_000
+            if large:
+                logger.info("UID %s 大邮件 (%d bytes)，用 PEEK 截断处理", uid, size)
+
+            # 大邮件用 PEEK 拉取，不触发服务器标记已读；小邮件正常拉
+            fetch_cmd = "BODY.PEEK[]" if large else "RFC822"
+            _, msg_data = conn.uid("FETCH", uid, fetch_cmd)
             if msg_data[0] is None:
                 logger.warning("UID %s FETCH 返回空，跳过", uid)
                 continue