GPU detection refactor:
- Major rewrite of gpu_detector.go with unified detection interface
- Support for NVIDIA (NVML), AMD (ROCm), and Apple Metal
- Runtime GPU capability querying for scheduler matching
macOS improvements:
- gpu_macos.go: native Metal device enumeration and memory queries
- Support for Apple Silicon (M1/M2/M3) unified memory reporting
- Fallback to system profiler for Intel Macs
Testing infrastructure:
- Add gpu_detector_mock.go for testing without hardware
- Update gpu_golden_test.go with platform-specific expectations
- Cross-platform GPU info validation
Update worker system for scheduler integration:
- Worker server with scheduler registration
- Configuration with scheduler endpoint support
- Artifact handling with integrity verification
- Container executor with supply chain validation
- Local executor enhancements
- GPU detection improvements (cross-platform)
- Error handling with execution context
- Factory pattern for executor instantiation
- Hash integrity with native library support
- Surface GPUDetectionInfo from parseGPUCountFromConfig for detection metadata
- Document FETCH_ML_TOTAL_CPU and FETCH_ML_GPU_SLOTS_PER_GPU env vars
- Add debug logging for all env var overrides to stderr
- Track config-layer auto-detection in GPUDetectionInfo.ConfigLayerAutoDetected
- Add --include-all flag to artifact scanner (includeAll parameter)
- Add AMD production mode enforcement (error in non-local mode)
- Add GPU detector unit tests for env overrides and AMD aliasing
