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

activate.ps1

@@ -0,0 +1 @@
+Start-Process -WindowStyle Normal -FilePath "powershell" -ArgumentList "-NoExit", "-Command", "& '.\.venv\Scripts\Activate.ps1'"