feat(production-excellence): add thin production-excellence bundle (#228)

Add the production-excellence bundle (#195) that composes cross-domain
production evidence (readiness, migration, recovery, capacity/cost,
incident-learning) into a launch or operational decision — go, no-go,
defer, exception, or escalation — with an accountable owner and a
post-launch learning path.

- SKILL.md: thin umbrella with readiness routing table (5 primary
  production-domain routes + 7 supporting specialists), cross-domain
  entry evidence, gate/exception model, operational handoff, and
  post-launch learning paths routed to incident-learning and
  product-lifecycle-learning.
- AGENTS.md: nested-skill loading behavior and harness compatibility.
- README.md: human-facing with all five required sections.
- references/discovery-brief.md: bounded comparison with 13 existing
  production and release skills (SRE, release, platform, security,
  data, QA, verification, lifecycle-learning, plus milestone skills).
- references/evidence-packet.md: production evidence packet covering
  readiness, migration, recovery, capacity/cost, and incident-learning
  domains — for both new services and changes to existing systems.
- references/gates.md: gate/exception model with go, no-go, defer,
  exception, escalation outcomes, each anchored to service ownership,
  risk, evidence, and verification.
- references/handoff-record.md: operational handoff fields and
  post-launch learning path.
- evals/evals.json: 5 integrated cases covering normal release,
  blocked launch (untested rollback), data migration, dependency
  outage, and cost/SLO conflict.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

.codex-plugin/plugin.json

@@ -30,6 +30,7 @@
     "./brand-designer",
     "./bundles/neckbeard",
     "./bundles/product-lifecycle",
+    "./bundles/production-excellence",
     "./bundles/research-and-vault",
     "./bundles/tailscale",
     "./bundles/workflow-architect",