feat(sdlc): staging environment + automated staging→prod pipeline

- pr-checks.yml: PR gate — frontend typecheck+jest, backend import smoke,
  image builds (no push), Claude AI review posted as PR comment (severe
  findings block merge)
- deploy.yml (replaces build-and-push.yml): merge to main builds+pushes
  images tagged sha-<sha>/staging, deploys the staging Portainer stack via
  webhook, runs Playwright E2E journeys against staging, then retags the
  verified images :prod (previous kept as :prod-previous) and deploys prod
- docker-compose.portainer.staging.yml: second Portainer stack — :staging
  images, sc_staging_* names, own macvlan IPs, Airflow on 8081; data
  bootstrapped from source via the staging Airflow DAGs
- prod compose now pins :prod instead of :latest (only the promotion step
  moves it; :latest is no longer published)
- e2e/: 6 Playwright journeys (search, postcode, detail, compare, rankings)
  driven by BASE_URL — the promotion gate
- scripts/ci/ai_review.py: Claude review with structured JSON findings
- docs/DEPLOY.md: full SDLC doc incl. one-time setup checklist and rollback
- replaced removed 'next lint' with tsc typecheck; fixed stale jest tests
  (slug URLs, N/A formatting, stable trend, fake-timer setup)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PqGhF93UrpDNvXBLMjJENL

claude.md

@@ -105,8 +105,22 @@ This starts:
 - `GET /api/metrics` - Metric definitions (single source of truth)
 - `GET /api/data-info` - Database stats
 
+## SDLC
+
+Full details in `docs/DEPLOY.md`. The short version:
+
+- **Never push to `main` directly.** Work on a feature branch and open a PR;
+  branch protection requires the PR checks (typecheck, tests, builds, AI review)
+  to pass before merge.
+- Merging to `main` deploys automatically: images are built once, deployed to
+  the **staging** Portainer stack, verified by the Playwright journeys in
+  `e2e/`, and only then retagged `:prod` and rolled out to production.
+- If you change user-facing behaviour, update or extend the `e2e/` journey
+  tests in the same PR — they are the promotion gate.
+
 ## Recent Changes
 
+- Added staging environment + automated staging→prod pipeline (Gitea Actions)
 - Migrated from CSV file storage to PostgreSQL database
 - Added location-based search using postcode geocoding
 - Added local authority filter to rankings