feat: init AI email summarization bot

- Multi-account IMAP email polling with UID tracking
- DeepSeek API integration with JSON Mode structured output
- Telegram notification with formatted MarkdownV2 message
- YAML config with dataclass-based type validation
- Graceful shutdown on SIGINT/SIGTERM
- 60s default polling interval

src/email_client.py

@@ -0,0 +1,86 @@
+import imaplib
+import email
+from email.header import decode_header
+from email.utils import parsedate_to_datetime
+from typing import Optional
+from src.config import EmailAccount
+
+
+class Email:
+    def __init__(self, uid: bytes, subject: str, sender: str, body: str, date: str):
+        self.uid = uid
+        self.subject = subject
+        self.sender = sender
+        self.body = body
+        self.date = date
+
+
+def _decode_str(s: str) -> str:
+    parts = decode_header(s)
+    result = []
+    for part, charset in parts:
+        if isinstance(part, bytes):
+            try:
+                result.append(part.decode(charset or "utf-8", errors="replace"))
+            except LookupError:
+                result.append(part.decode("utf-8", errors="replace"))
+        else:
+            result.append(part)
+    return "".join(result)
+
+
+def _get_text_from_msg(msg) -> str:
+    if msg.is_multipart():
+        for part in msg.walk():
+            content_type = part.get_content_type()
+            if content_type == "text/plain":
+                payload = part.get_payload(decode=True)
+                if payload:
+                    return payload.decode("utf-8", errors="replace")
+            elif content_type == "text/html":
+                payload = part.get_payload(decode=True)
+                if payload:
+                    return payload.decode("utf-8", errors="replace")
+    else:
+        payload = msg.get_payload(decode=True)
+        if payload:
+            return payload.decode("utf-8", errors="replace")
+    return ""
+
+
+def fetch_unseen_emails(account: EmailAccount) -> list[Email]:
+    conn = imaplib.IMAP4_SSL(account.imap_server, account.imap_port)
+    conn.login(account.username, account.password)
+    conn.select("INBOX")
+
+    _, data = conn.uid("SEARCH", None, "UNSEEN")
+    uids = data[0].split() if data[0] else []
+    emails = []
+
+    for uid in uids:
+        _, msg_data = conn.uid("FETCH", uid, "RFC822")
+        if msg_data[0] is None:
+            continue
+        raw_email = msg_data[0][1]
+        msg = email.message_from_bytes(raw_email)
+
+        subject = _decode_str(msg.get("Subject", ""))
+        sender = _decode_str(msg.get("From", ""))
+        date_str = msg.get("Date", "")
+        body = _get_text_from_msg(msg)
+
+        emails.append(Email(uid=uid, subject=subject, sender=sender, body=body, date=date_str))
+
+    conn.logout()
+    return emails
+
+
+def mark_as_seen(account: EmailAccount, uids: list[bytes]):
+    if not uids:
+        return
+    conn = imaplib.IMAP4_SSL(account.imap_server, account.imap_port)
+    conn.login(account.username, account.password)
+    conn.select("INBOX")
+    for uid in uids:
+        conn.uid("STORE", uid, "+FLAGS", "\\Seen")
+    conn.logout()