test(e2e): add playwright e2e stand with test pocketbase and axe checks

- playwright.config.ts: test PocketBase (port 8190) and ng serve (port 4300)
  as webServers, SIGTERM shutdown so the stand removes its temp dir
- fixtures: user via open registration, api SDK client, signedInPage with pb_auth cookie
- expectNoA11yViolations runs all axe rules (WCAG and best-practice)
- render home route on the server; main and h1 placeholder in app shell
- config tests for playwright.config.ts in test:lint; docs updated

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/e2e/urls.ts

@@ -0,0 +1,4 @@
+// Адреса стенда e2e: порты не пересекаются с `pnpm pb:serve` (8090) и `pnpm start` (4200).
+export const E2E_PB_PORT = 8190;
+export const E2E_PB_URL = `http://127.0.0.1:${E2E_PB_PORT}`;
+export const E2E_APP_URL = 'http://localhost:4300';