ci: richer step reports via Gitea 1.27 job summaries (closes #136) (#137)

## What & why

Use the standard `$GITHUB_STEP_SUMMARY` (Gitea 1.27 + act_runner 2.0.0) to surface on the run page what was previously buried in logs or download-only artifacts. All five quick wins from #136, **reporting-only** — no job's pass/fail gating changes.

Closes #136

### Items

1. **Mutation scores** — added the `markdown` reporter to each `stryker-config.json`; the `mutation` job concatenates each service's `mutation-report.md` into the summary (`if: always()`). Also reveals where `make mutation` stopped on a ratchet break.
2. **Per-frontend tests** — the 4 apps' `test` targets emit vitest JSON to `test-output/{projectName}.json` (Nx token interpolation); `infra/vitest-summary.py` renders a per-frontend table.
3. **Per-service unit tests** — `make unit` now writes TRX; `infra/trx-summary.py` renders a per-service table (service name derived from the `services/<name>/` path, so `domain` shows, not `big.tests`).
4. **e2e per-spec results** — Playwright writes `playwright-report.json`; `run-e2e-check.sh` copies it out of the container (capturing the exit code first); `infra/playwright-summary.py` renders a per-spec table. Turns a red e2e into a one-glance "which spec".
5. **verify-stack check table** — each live-stack check has an `id`; a final `if: always()` step tabulates each check's ✅/❌/⏭️.

Docs: `gitea-actions-gotchas.md` §8 (version requirement + `$GITHUB_STEP_SUMMARY` guard + step-level `always()` note).

### Notes

- Every summary write is guarded with `[ -n "${GITHUB_STEP_SUMMARY:-}" ]`, so it no-ops on an unsupported runner / locally.
- New helper scripts are stdlib-only Python, matching the existing `infra/*.py` check scripts (no new dependency — a few lines of parsing rather than a test-logger package).
- `TestResults/` and `test-output/` gitignored.
- This is also the first PR-run exercising the #135 verify-stack fix end to end.

## Verified locally

`make unit` (TRX) ✓ · 4 apps' vitest JSON ✓ · ACL Stryker markdown report ✓ · all four parsers + the two summary shell blocks ✓ · `ci.yaml` + `run-e2e-check.sh` syntax ✓. The rendered summaries themselves only appear on the run page — this PR's CI run is the end-to-end check.

## Definition of Done

- [x] Each item writes to `$GITHUB_STEP_SUMMARY` (guarded), renders on the run page.
- [x] No change to any job's pass/fail gating.
- [x] Conventional Commits referencing #136 (one per item + docs).
- [ ] CI green; summaries visible on the run.
- [x] Runbook note (gotchas §8).

🤖 Generated with [Claude Code](https://claude.com/claude-code)Reviewed-on: #137

tests/e2e/playwright.config.ts

@@ -21,7 +21,9 @@ export default defineConfig({
   // OOM-killed mid-action ("Page crashed") — fixing the flakiness at its source rather than leaning
   // on `retries` (CLAUDE.md §15). Only two long-running happy-path specs, so serial costs little.
   workers: 1,
-  reporter: [['list']],
+  // `list` for the live log; `json` (→ /e2e/playwright-report.json in the container) is copied out
+  // by run-e2e-check.sh and rendered as a per-spec table in the CI job summary (#136).
+  reporter: [['list'], ['json', { outputFile: 'playwright-report.json' }]],
   use: {
     baseURL,
     trace: 'on-first-retry',