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/integration/instance-sync.test.ts

@@ -18,11 +18,8 @@ import type { TestDb } from '../helpers/db';
 // ---------------------------------------------------------------------------
 
 const ctx = vi.hoisted(() => {
-  // eslint-disable-next-line @typescript-eslint/no-require-imports
   const { mkdirSync } = require('node:fs');
-  // eslint-disable-next-line @typescript-eslint/no-require-imports
   const { join } = require('node:path');
-  // eslint-disable-next-line @typescript-eslint/no-require-imports
   const { tmpdir } = require('node:os');
   const dir = join(tmpdir(), `instance-sync-test-${Date.now()}`);
   mkdirSync(dir, { recursive: true });