test(dashboard): stabilize the e2e suite under parallel runs

Three issues found while running the full B1–B8 suite together:

- The B1 logout test was driving the shared admin storageState
  token, invalidating it for every subsequent test. Switched it to
  a fresh login so its session is disposable.
- Bumped navigationTimeout to 30s and capped local workers at 4 to
  cope with the Vite dev server's first-compile cost under
  parallel load. Local also gets one retry to absorb intermittent
  warmup flakiness.
- Cleared a few lint warnings (unused appId / _adminPage vars) and
  belt-and-braces gitignore for playwright artifacts written to
  the repo root when the CLI is invoked from there by accident.

Suite now: 55/55 passing in ~21s.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -36,6 +36,10 @@ config.local.toml
 /dashboard/playwright-report
 /dashboard/test-results
 /dashboard/.playwright
+# When playwright is invoked from the repo root by accident, these
+# also land here.
+/playwright-report
+/test-results
 
 # Caddy
 /caddy/data