Telegram clients send /start when a user first DMs a bot (and when they
tap "Start" on a bot profile). It's a platform handshake, not a
user-intended prompt — forwarding it to the agent wastes a turn and
produces a confused response.
Matches the existing filter pattern for /help, /login, /logout,
/doctor, /config.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>