refactor(skills): mirror groombook sdlc structure, split devops skill

- sdlc: trim to application-repo scope with Phase 1-5 pipeline; engineer
  self-merges all branches with per-branch prerequisites; move infra,
  Flux, tofu, and operator-install content out
- devops: new skill mirroring groombook/org/skills/devops — owns
  cartsnitch/infra, Flux GitOps, OpenTofu controller, cluster topology,
  Flux Image Tag Automation denied policy
- safety: add Gitea-origin board-approval gate, board-approval scope
  section, and adapterConfig.env read-before-write rule
- coding-standards: replace "no agent merges their own PR" with the
  reviews-required-then-engineer-may-merge rule consistent with sdlc
- CLAUDE.md: update skill index, branch & merge policy, and SDLC phase
  summary to reflect engineer-self-merge and the new devops skill

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

skills/coding-standards/SKILL.md

@@ -24,7 +24,7 @@ When making technical decisions, prioritize in this order:
 ## Pull request discipline
 
 * All changes go through a PR. **Never push directly to `dev`, `uat`, or `main`.**
-* No agent merges their own PR.
+* Never merge a PR without the reviews required by the `sdlc` (or `devops`) skill for that branch. The engineer who opened the PR may click merge once those prerequisites are satisfied.
 * Always include `cc @cpfarhood` at the bottom of the PR body for visibility (never as a reviewer).
 * Engineers always target `dev` — never `uat` or `main` directly.