rpdfium-binary

https://github.com/retsef/rpdfium

Companion gem for `rpdfium` that ships precompiled PDFium shared libraries (Apache-2.0/BSD-3-Clause) from bblanchon/pdfium-binaries. Mirrors the pypdfium2 wheels approach: each platform-specific gem includes its native library directly, while the generic Ruby-platform gem falls back to a runtime download.