- Add user repository functions for project user CRUD
- Create platform-user-service for project user management
- Add GET /v1/platform/projects/:id/users endpoint
- Add POST /v1/platform/projects/:id/users endpoint
- Support project_admin and manager roles
- Validate username uniqueness and project existence
- Normalize real_name and phone inputs
- Add comprehensive test coverage (13 tests)
- Fix test isolation issue in platform-projects cleanup
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>