test(e2e): add Playwright suite for auth + CSRF + visibility fixes

Covers the security fixes that landed across both repos:

- auth.spec.ts: login persists nz-jwt cookie and getProfile succeeds;
  password change bumps TokenVersion + revokes the old cookie so the
  pre-change JWT can no longer auth (regression guard for the
  keyId+session backend rewrite).
- cron-csrf.spec.ts: POST /api/v1/cron/:id/manual succeeds while GET
  is no longer routable (regression guard for the cron CSRF fix).
- fm-csrf.spec.ts: POST /api/v1/file is reachable while GET is no
  longer routable (regression guard for the FM CSRF fix).
- visibility.spec.ts: an anonymous caller cannot see a server-group
  that contains zero guest-visible servers (regression guard for the
  server-group leak fix).

Fixtures wrap the noisy login + cleanup boilerplate. tsconfig is
scoped to tests/e2e so the suite stays out of the production tsc
project graph.

Playwright config starts the Vite dev server (npm run dev) and
expects a backend reachable at the URL Vite proxies to. CI workflow
follow-up commit wires the backend up.

Co-authored-by: cloudcode <cloudcode@users.noreply.github.com>

.gitignore

@@ -24,3 +24,9 @@ dist-ssr
 *.sw?
 bun.lock
 pnpm-lock.yaml
+
+# Playwright
+/playwright-report
+/test-results
+/blob-report
+/playwright/.cache