Add comprehensive integration and end-to-end test suites:
- Integration tests for API flows (authorization, token, verification)
- Integration tests for middleware chain and security headers
- Integration tests for domain verification services
- E2E tests for complete authentication flows
- E2E tests for error scenarios and edge cases
- Shared test fixtures and utilities in conftest.py
- Rename Dockerfile to Containerfile for Podman compatibility
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
