Dockerfile.test for CI: builds Skia from source on Linux ARM64/x86,
runs all 49 Rust tests with CPU raster + FFmpeg libx264 fallback.
Includes ninja, python3, clang for Skia source build, plus fonts
and FFmpeg for rendering tests.
Supports: `docker run hyperframes-native:test` (tests)
`docker run hyperframes-native:test bench` (benchmarks)