Channel messages address the agent with a leading @mention (e.g. '@Chip
/whoami'). The adapter passed the raw content through, so the gateway's
is_command() check (text.lstrip().startswith('/')) never matched and slash
commands were routed as plain chat. Strip a leading mention (name, npub, or
hex form) before dispatch in channels, mirroring the Discord adapter. Also
cleans normal prompts ('@Chip what's up?' -> 'what's up?'). DMs are untouched.
Verified live: '@Chip /whoami' -> '/whoami' after connect populates identity.
Refs #68871
Rob Zehner
65f52d4913