Wire mattpocock skills into engineering docs, fix stale misc README

Adds the 8 already-copied engineering skills (ask-matt, codebase-design,
domain-modeling, implement, prototype, resolving-merge-conflicts,
setup-matt-pocock-skills, triage) plus frontend-design to
engineering/README.md and plugin.json. Also rewrites misc/README.md,
which listed 3 skills with no matching folder and was missing 3 real ones.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

skills/misc/README.md

@@ -2,7 +2,11 @@
 
 Tools I keep around but rarely use.
 
-- **[git-guardrails-claude-code](./git-guardrails-claude-code/SKILL.md)** — Set up Claude Code hooks to block dangerous git commands (push, reset --hard, clean, etc.) before they execute.
-- **[migrate-to-shoehorn](./migrate-to-shoehorn/SKILL.md)** — Migrate test files from `as` type assertions to @total-typescript/shoehorn.
-- **[scaffold-exercises](./scaffold-exercises/SKILL.md)** — Create exercise directory structures with sections, problems, solutions, and explainers.
-- **[setup-pre-commit](./setup-pre-commit/SKILL.md)** — Set up Husky pre-commit hooks with lint-staged, Prettier, type checking, and tests.
+## Model-invoked
+
+Model- or user-reachable (rich trigger phrasing so the model can reach for them).
+
+- **[codex-debugging](./codex-debugging/SKILL.md)** — Investigate Codex CLI/app-server behavior, config parsing, tool behavior, prompts, and MCP wiring bugs.
+- **[git-guardrails-claude-code](./git-guardrails-claude-code/SKILL.md)** — Set up Claude Code hooks to block dangerous git commands (push, reset --hard, clean, branch -D, etc.) before they execute.
+- **[github-deep-review](./github-deep-review/SKILL.md)** — Evidence-first review of a bug or PR: read the code, find the real cause, decide the best fix, and say "not proven" when the trail is weak.
+- **[github-project-triage](./github-project-triage/SKILL.md)** — Triage a GitHub project's issues/PRs into maintainer-facing item cards: what it's about, risk, proof/test state, blockers, next action.