fix(ci): e2e — let Playwright manage both servers (fixes the 2-hour hang)

The e2e job backgrounded `dotnet run &` and `ng serve &` in separate Actions
steps, then `npx wait-on` (no timeout) in a later step. A process started with
`&` in one step is killed when that step's shell exits, so wait-on waited forever
on servers that were already gone — the job hung until the runner's hard limit
(~2h; Gitea's act_runner doesn't reliably enforce timeout-minutes).

Move both servers into Playwright's `webServer` (an array: backend + `npm start`),
so Playwright starts them, waits for readiness, runs the suite, and tears them
down in the one `npm run e2e` process — CI and local alike. The CI e2e job is now
just npm ci / playwright install / npm run e2e. `reuseExistingServer` is on locally
(reuses a running app, incl. the docker stack) and off in CI (fresh start).

Verified locally via `CI=1 npm run e2e` against free ports + a clean db: both
smoke tests pass in ~15s (no hang). The earlier local failure was leftover SQLite
state (WP-22) from a dirty run resuming a Concept — CI checks out fresh, so its db
is always empty.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -68,6 +68,11 @@ jobs:
     # runner checkout per run, so there's no bigregister.db (WP-22, gitignored)
     # left over from a prior run to leak state in; the backend creates + migrates
     # an empty one on this boot, same as a fresh clone always has.
+    # Playwright's `webServer` (playwright.config.ts) starts BOTH the backend and
+    # `ng serve`, waits for them, runs the suite, and tears them down — all in the
+    # one `npm run e2e` process. Do NOT background them as separate steps: a `&`
+    # process from one Actions step is dead by the next step, so `wait-on` hung
+    # forever (the 2-hour e2e hang).
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
@@ -81,9 +86,6 @@ jobs:
           dotnet-version: 10.0.x
       - run: npm ci
       - run: npx playwright install --with-deps chromium
-      - run: dotnet run --project backend/src/BigRegister.Api --urls http://localhost:5000 &
-      - run: npx ng serve --proxy-config proxy.conf.json &
-      - run: npx wait-on http://localhost:5000/swagger http://localhost:4200
       - run: npm run e2e
 
   codeql: