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

docs/runbooks/gitea-actions-gotchas.md

@@ -221,3 +221,27 @@ fails", prefer serialising with a `concurrency` group over `needs` + `always()`.
 **Also** — a run already stuck this way will **not** clear itself; force-cancel it
 from the Actions UI (plain cancel can also stall on this version, #35782). Push the
 workflow fix to produce a fresh run.
+
+---
+
+## 8. Job summaries (`$GITHUB_STEP_SUMMARY`) need Gitea ≥1.27 + runner ≥2.0
+
+Markdown a step appends to the `$GITHUB_STEP_SUMMARY` file renders on the run page
+(no artifact download). We use it for per-run reports (#136): mutation scores
+(Stryker `markdown` reporter), per-service unit results (`infra/trx-summary.py` over
+TRX), per-frontend results (`infra/vitest-summary.py` over each app's vitest JSON),
+the verify-stack check table, and per-spec e2e results (`infra/playwright-summary.py`).
+
+**Requirements / conventions:**
+
+- Requires **Gitea ≥ 1.27** (stores/renders summaries) and **act_runner ≥ 2.0.0**
+  (uploads them). Older pairings silently skip the upload.
+- **Guard every write:** `[ -n "${GITHUB_STEP_SUMMARY:-}" ] || exit 0` — on a runner
+  without support the var is unset and `>> "$GITHUB_STEP_SUMMARY"` would be an
+  ambiguous-redirect error. The guard makes the step a no-op locally / on old runners.
+- Use `if: always()` (step-level) on summary steps so they render even when the thing
+  they report on failed. Step-level `always()` is fine on 2.0.0 — unlike the *job*-level
+  status-function `if` of §7.
+- Getting a report out of the e2e container: Playwright writes `playwright-report.json`
+  inside the container; `infra/run-e2e-check.sh` `docker cp`s it back to the host
+  (capturing the test exit code first) so the summary step can read it.