v0.1.1

Added

• add butteraugli metric
• vendor lcms2, building it from source by default
• add native SSIM metric

Fixed

• initialize Butteraugli shim's uninitialized SIMD row padding
• make lcms2 backends a structural XOR

Other

• classify *.ppm as binary in .gitattributes
• harden butteraugli wrapper coverage
• numerically cross-validate butteraugli against libjxl v0.8.2
• add package-size & FFI-compiles-away check (#6)