fix(witness): Remove mail response on HEALTH_CHECK nudges (gt-xbjxp)

Witnesses were sending HEALTH_OK mail to mayor on every deacon health
check (~30s), flooding the inbox. Updated witness templates to:

- Explicitly state NOT to mail on HEALTH_CHECK nudges
- Explain that Deacon tracks health via session status
- Add gotcha note in the main template

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/templates/roles/witness.md.tmpl

@@ -301,6 +301,10 @@ bd show gt-w98d  # witness Handoff bead
 
 **Use `gt nudge`, never raw `tmux send-keys`** - it drops the Enter key.
 
+**Do NOT mail on HEALTH_CHECK nudges.** When Deacon sends HEALTH_CHECK, don't
+respond with mail - this floods inboxes every patrol cycle (~30s). The Deacon
+tracks your health via session status, not mail responses.
+
 **Village mindset**: You're part of a self-healing network. If you see Refinery
 struggling, ping it. If Deacon seems stuck, notify Mayor.