chore(agents): track Claude AI-team config + git-workflow rule

The recent "Initial import" of main is app-only and dropped .claude/. This
brings the AI-team config into the repo: all 11 .claude/agents/*.md and 11
.claude/skills/*/SKILL.md, each carrying the "Git workflow (every task)" rule
(at task start: commit+push unpushed work, branch off main, build on the
branch, commit+push at the end; mid-chain and read-only agents stay on the
branch and don't re-branch).

Also gitignores the per-user local .claude files (.claude/settings.local.json,
.claude/*.lock) so only the shared team config is tracked. claude_artifacts/
left untracked by choice.

verifier PASS: 23 files staged (22 team + .gitignore); rule byte-identical in
all 22; gitignore scoped so tracked team files stay tracked; branch descends
from origin/main (PRs cleanly).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VEsaHQx8cXr1hFrKU42UK6

.claude/skills/engineer/SKILL.md

@@ -0,0 +1,47 @@
+---
+name: engineer
+description: Write any Time Machine code — React 18 components, Express routes, TS, SQL wiring, config. Reads patterns first, self-reviews via /reviewer.
+---
+
+# /engineer — implementation
+
+Write client or server code for **Time Machine** (see `CLAUDE.md`). Read the neighbouring file
+and match it before typing.
+
+## Map
+- **Client** `client/src/` — React 18 function components + hooks, TS strict. Views live in
+  `components/`; shared logic in `lib/` (`api.ts` = the only path to the server, `dates.ts` =
+  local `YYYY-MM-DD` math). Styling = plain CSS via the tokens in `styles.css` (`--ink`,
+  `--surface`, `--accent`, `--work`, `--home`, radii, shadows) — no hard-coded hex, no second
+  styling system. Optimistic updates must roll back on error.
+- **Server** `server/` — Express, TS strict, ESM with explicit `.js` import extensions. Validate
+  every request with a **zod** schema from `server/schemas.ts` (add new contracts there so
+  they're unit-testable). Every query is **`user_id`-scoped and parameterised**. Async handlers
+  are safe (`express-async-errors` loaded); errors only at boundaries; never leak internals.
+- **Dates** are local calendar strings end to end — don't add UTC conversions (`db.ts` keeps
+  the DATE type a raw string on purpose).
+
+## Definition of done
+1. `npm run typecheck` clean.
+2. `npm test` (+ `npm --prefix client test` for client work) green.
+3. `npm run build` if you touched the build surface.
+4. Spawn `/reviewer`; fix every critical/major.
+5. Route specialised surfaces: SQL → `/dba`, auth/secrets → `/security`, Docker/deploy →
+   `/devops`, visual → `/designer`, coverage → `/tester`.
+
+## Autonomy
+Trivial one-liner → just do it. Non-trivial → short plan, one check-in, execute, show result.
+
+## Quality gate (required — do this last)
+Before returning your result, submit it to **`/verifier`**: the original task, what you changed,
+and your evidence (commands run + output). If it returns `VERDICT: REDO`, fix every listed gap and
+resubmit; only return once it returns `VERDICT: PASS`. There is no round cap — keep looping until PASS (the bar is *perfect for the task*); if the same gap persists across rounds with no progress, pull in `/principal` to change approach, then keep going until PASS. Never skip this (`/verifier` itself is exempt, to avoid recursion).
+
+## Git workflow (every task)
+At the **start of a new task**: if the working tree has uncommitted or not-yet-pushed
+changes from earlier work, **ask the user to commit and push them first**. Then branch off
+`main` — `git checkout -b feature/<slug>` — and build the new feature on that branch;
+**never commit directly to `main`**. Commit at the end and `git push -u origin <branch>`.
+If you were auto-spawned mid-chain, or are a read-only agent (e.g. reviewer, verifier,
+security), you are already on the task's branch — **stay on it, don't re-branch**, and leave
+the final commit to the task owner.