Production telemetry: log error monitoring + in-bot feedback

Deferred by explicit request (2026-06-12) — for a future PR:

- **Active log monitoring**: watch prod logs for error patterns and surface them (e.g. notify the owner via Telegram) instead of waiting for users to report breakage.
- **In-bot feedback**: let users submit bug reports and feature requests directly via Telegram (e.g. a /feedback command), forwarded to the owner.