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>
Implements PHP SDK generator using Docker-only approach:
- Requires Docker with openapitools/openapi-generator-cli
- No native PHP generator tool; Docker is the only option
Includes tests following _Good convention for Available and Generate.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>