feat(test): M5.3 — Playwright e2e harness for the dev stack

Adds the M5.3 deliverable scoped to local-dev (stage doesn't exist yet,
so the CI e2e job is gated behind the repo variable RUN_E2E='true' —
defaults off).

Layout:
  playwright.config.ts   chromium project; baseURL defaults to
                         http://acme.localhost:3000 (subdomain routing
                         fires). PLAYWRIGHT_BASE_URL / APEX_URL / etc.
                         env vars override for stage.
  tests/e2e/apex.spec.ts        landing page renders
  tests/e2e/tenant.spec.ts      signed-out dashboard shows Sign in
                                button; unknown slug returns 404
  tests/e2e/health.spec.ts      every dev-stack endpoint reachable
                                (portal /api/auth/providers, tenant-
                                registry /healthz, KC realm metadata)

Run locally with the full dev stack up:

  cd platform/orca-platform && make dev-up
  cd platform/tenant-registry && make dev
  cd platform/portal && make dev
  cd platform/portal && make e2e

OIDC click-through not asserted yet — Keycloak in headless mode is
flaky and depends on a stable test-user password. The current gate
(Sign-in button visible) catches the more common 'auth completely
broken' regression; the deeper smoke lands when stage has its own
test fixture.

tsconfig now excludes tests/e2e so vitest + tsc don't fight over
Playwright type imports.

Refs: M5.3

.gitea/workflows/ci.yaml

@@ -87,7 +87,11 @@ jobs:
   e2e:
     needs: test
     runs-on: docker
-    if: hashFiles('playwright.config.ts','playwright.config.js') != '' && github.event_name == 'push' && github.ref == 'refs/heads/main'
+    # Two gates: playwright.config.ts must exist + the repo variable
+    # RUN_E2E must be 'true'. Until stage.breakpilot.com is up (M1.2 +
+    # M0.3), the e2e job is opt-in. Locally, devs run `make e2e` against
+    # their own dev stack.
+    if: hashFiles('playwright.config.ts','playwright.config.js') != '' && github.event_name == 'push' && github.ref == 'refs/heads/main' && vars.RUN_E2E == 'true'
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
@@ -98,7 +102,8 @@ jobs:
       - run: pnpm exec playwright install --with-deps chromium
       - run: pnpm e2e
         env:
-          PLAYWRIGHT_BASE_URL: https://stage.breakpilot.com
+          PLAYWRIGHT_BASE_URL: ${{ vars.STAGE_PORTAL_BASE_URL }}
+          PLAYWRIGHT_APEX_URL: ${{ vars.STAGE_PORTAL_APEX_URL }}
           PLAYWRIGHT_TEST_USER: ${{ secrets.STAGE_TEST_USER }}
           PLAYWRIGHT_TEST_PASS: ${{ secrets.STAGE_TEST_PASS }}