Function pdfium_cache_dir 

pub fn pdfium_cache_dir() -> PathBuf

Returns the per-version cache directory for the PDFium library.

Default locations:

• macOS: ~/Library/Caches/pdf2md/pdfium-{VERSION}/
• Linux: ~/.cache/pdf2md/pdfium-{VERSION}/
• Windows: %LOCALAPPDATA%\pdf2md\pdfium-{VERSION}\

Override by setting PDFIUM_AUTO_CACHE_DIR.