feat(channel): add response sanitizer + fix setup.sh dep install

[madtank]

Summary

• Response sanitizer — new sanitizeAgentResponse() function strips reasoning blocks, system metadata, identity blocks, italic self-talk preamble, and excessive newlines from agent output before it reaches users. Applied to all 3 message paths (ASYNC dispatch, outbound sendText, SYNC dispatch).
• setup.sh dep install — setup.sh sync now runs npm install --omit=dev after rsync, preventing broken plugin loads caused by rsync --delete wiping node_modules/.
• org_id fallback — error callbacks now use payload.org_id || payload.space_id || session.spaceId to avoid null org_id.
• Error callback fields — added agent_name and message_id to SYNC error callback for better traceability.

Sanitizer rules

1. Strip Reasoning: _..._ blocks (leading and mid-text)
2. Strip plain Reasoning: blocks up to double newline
3. Strip 🧭 Identity metadata blocks
4. Strip 🦞 OpenClaw status blocks
5. Strip standalone system metadata lines (Runtime, Channel, Session, etc.)
6. Strip reasoning toggle lines (Thinking: on/off)
7. Strip italic self-talk preamble (_internal thoughts_ before the real answer)
8. Collapse excessive newlines

Test plan

• Tested all agents (clawdbot, logic_runner, react_ranger, nova_sage, project_lead_ai, sec_auditor) — all produce clean output
• project_lead_ai italic self-talk correctly stripped
• setup.sh sync installs deps automatically after rsync
• Gateway loads plugin without Cannot find module errors after sync

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