Previously, fastembed created .fastembed_cache in the current working
directory, polluting project folders with symlinks.
Now uses platform-appropriate cache directories:
- macOS: ~/Library/Caches/com.vestige.core/fastembed
- Linux: ~/.cache/vestige/fastembed
- Windows: %LOCALAPPDATA%\vestige\cache\fastembed
Can still be overridden with FASTEMBED_CACHE_PATH env var.
Fixes user feedback about .fastembed_cache appearing in random folders.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>