- Add proxy config field for Telegram channel to support HTTP/SOCKS proxies
- Use telego.WithHTTPClient to route all Telegram API requests through proxy
- Add FlexibleStringSlice type so allow_from accepts both strings and numbers
- Improve IsAllowed to match numeric ID, username, and @username formats
- Update config.example.json with proxy field
Extract common file download and audio detection logic to utils package,
implement consistent temp file cleanup with defer, add allowlist checks
before downloading attachments, and improve context management across
Discord, Slack, and Telegram channels. Replace logging with structured
logger and prevent context leaks in transcription and thinking animations.
Multiple packages had their own private truncate implementations:
- channels/telegram.go: truncateString (byte-based, no "...")
- channels/dingtalk.go: truncateStringDingTalk (byte-based, no "...")
- voice/transcriber.go: truncateText (byte-based, with "...")
All three are functionally equivalent to the existing utils.Truncate,
which already handles rune-safe truncation and appends "..." correctly.
Replace all private copies with utils.Truncate and delete the dead code.
