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/engineering/README.md

@@ -14,6 +14,7 @@ Reachable only when you type them (`disable-model-invocation: true`).
 - **[to-issues](./to-issues/SKILL.md)** — Break any plan, spec, or PRD into independently-grabbable issues using vertical slices.
 - **[to-prd](./to-prd/SKILL.md)** — Turn the current conversation into a PRD and publish it to the issue tracker.
 - **[prototype](./prototype/SKILL.md)** — Build a throwaway prototype — a runnable terminal app for state/logic questions, or several toggleable UI variations.
+- **[implement](./implement/SKILL.md)** — Implement work from a PRD or set of issues: TDD at pre-agreed seams, typecheck and test as you go, then review and commit.
 
 ## Model-invoked
 
@@ -22,4 +23,6 @@ Model- or user-reachable (rich trigger phrasing so the model can reach for them)
 - **[diagnosing-bugs](./diagnosing-bugs/SKILL.md)** — Disciplined diagnosis loop for hard bugs and performance regressions: reproduce → minimise → hypothesise → instrument → fix → regression-test.
 - **[tdd](./tdd/SKILL.md)** — Test-driven development with a red-green-refactor loop. Builds features or fixes bugs one vertical slice at a time.
 - **[domain-modeling](./domain-modeling/SKILL.md)** — Actively build and sharpen a project's domain model — challenge terms, stress-test with scenarios, update `CONTEXT.md` and ADRs inline.
-- **[codebase-design](./codebase-design/SKILL.md)** — Shared discipline and vocabulary for designing deep modules: small interfaces, clean seams, testable through the interface.
+- **[codebase-design](./codebase-design/SKILL.md)** — Shared discipline and vocabulary for designing deep modules: small interfaces, clean seams, testable through the interface.
+- **[resolving-merge-conflicts](./resolving-merge-conflicts/SKILL.md)** — Work an in-progress git merge/rebase conflict hunk by hunk, resolving by intent, and always finish it (never `--abort`).
+- **[frontend-design](./frontend-design/SKILL.md)** — Build distinctive, production-grade frontend UI that avoids generic "AI slop" aesthetics.