fix: E2E select dropdown reliability and stale eslint-disable directives

- Fix Radix Select interaction in proxy host E2E helper: scroll trigger
  into view and wait for option visibility before clicking (fixes flaky
  access-control.spec.ts timeout)
- Apply same fix to certificate selector for consistency
- Remove stale eslint-disable directives from pre-existing test files
  (now covered by test-wide eslint config override)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/unit/l4-proxy-hosts-validation.test.ts

@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any */
 /**
  * Unit tests for L4 proxy host input validation.
  *