test(e2e): walking-skeleton Playwright happy path + verify-e2e lane (refs #68)

tests/e2e Playwright spec drives DigiD login (jan-burger/test123) → submit →
confirmation against the compose-served portal. run-e2e-check.sh runs it inside the
compose network (node container, browser installed at runtime) so the token issuer
(keycloak:8080) matches the BFF authority (ADR-0010). Wired as verify-e2e (Makefile +
verify chain + a verify-stack CI step).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -52,3 +52,8 @@ vite.config.*.timestamp*
 vitest.config.*.timestamp*
 
 .angular
+
+# Playwright e2e (installed/generated in-container or on local runs)
+tests/e2e/node_modules/
+tests/e2e/test-results/
+tests/e2e/playwright-report/