Docker containers were creating files as root, causing Go test cleanup
to fail with "permission denied". Now passes --user flag on Unix systems
to run containers as the current user.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Defines the common interface for SDK generators with:
- Generate(), Available(), Install() methods
- Registry for managing multiple generators
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>