Fix E2E test failures: strict mode violations and port conflicts

- Scope hero terminal locator to section.hero to avoid matching 3 terminal
  elements across the page (strict mode violation)
- Use h2-scoped filter for CLI CTA section to avoid matching multiple
  .cta-section elements containing "CLI" substring
- Change serve port from 3000/4001 to 4180 to avoid conflicts with other
  local services
- Add workers: 1 and reuseExistingServer to prevent server overload
- Add comprehensive E2E tests for navigation, sections, and app loading
- Add sections.spec.ts covering stats, showcase, mac-apps, features,
  ecosystem, packages, activity feed, and CTA sections

All 43 tests now pass.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: corvid-agent