Stability checkpoint — Grafana Cloud AI Observability POC (MR !188)

ADR-0059 : opt-in 3rd OTel traces exporter for Grafana Cloud AI
Observability. Spring AI 1.1+ emits GenAI semantic conventions
automatically (gen_ai.system, gen_ai.request.model, token usage,
latency) ; triple-export to LGTM local + GitLab Observability +
Grafana Cloud when env vars set. MIRADOR_AI_LOG_CONTENT opt-in for
prompt/completion text.

Bundles 5 CLAUDE.md rules from today's /insights session :
- Git Safety (no reset --hard without confirmation)
- CI/CD Scope (GitLab only, read logs before exploring config)
- Project Verification (state repo/branch/remote at start of response)
- Verify commands before suggesting (no hallucinated flags ; extra
  skepticism for meta-questions about Claude Code itself)
- Surgical fixes not allow_failure bypasses (tag-gate with JUnit @Tag
  or scope-out via rules:when:never)

Plus ship-mr skill (~/.claude/skills/ship-mr/SKILL.md) codifying the
end-to-end commit → push → MR → auto-merge → tag flow used across
100+ commits this week.