* fix: prevent meta tensor issues when accelerate is installed without GPU
When accelerate is installed but no GPU is available, transformers can
incorrectly use lazy loading (meta tensors) which fails when
sentence-transformers tries to move the model to a device.
The fix checks hardware and installed packages to determine the right
loading strategy:
- GPU available: device=None, device_map=None (auto-detect GPU)
- No GPU + accelerate: device='cpu', device_map='cpu' (force CPU loading)
- No GPU + no accelerate: device='cpu', device_map=None (normal CPU)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
* fix: add filelock for model initialization in parallel tests
When pytest-xdist runs multiple workers in parallel, they all try to
load models from the HuggingFace cache simultaneously, causing race
conditions and intermittent meta tensor errors.
Added filelock around embeddings and cross_encoder initialization in
conftest.py, similar to how pg0 database setup is serialized. Models
are now pre-initialized in the fixture before being passed to tests.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
* fix: add MPS support for macOS Apple Silicon
Extend GPU detection to include Apple MPS backend in addition to CUDA.
This ensures macOS users with Apple Silicon use MPS acceleration
instead of being incorrectly routed to the CPU fallback path.
