chore(agents): install mattpocock skills + per-repo agent config

- 38 skills from mattpocock/skills into .agents/skills/ (symlinked into
  .claude/skills/ for Claude Code)
- skills-lock.json for reproducible installs
- docs/agents/: issue-tracker (Gitea via tea CLI), triage-labels
  (default five-role vocabulary), domain docs (single-context)
- CLAUDE.md: add '## Agent skills' section pointing at docs/agents/
- .gitignore: un-ignore docs/agents/ under the local /docs/* rule

.gitignore

@@ -8,7 +8,8 @@ database/target
 # Server-local TTS pronunciation overrides (tts_pronunciations.example.json is the template)
 /tts_pronunciations.json
 /tmp
-/docs
+/docs/*
+!/docs/agents/
 /specs
 
 # Default ignored files