PipelineCacheValidation drives Device::PipelineCacheDataCompatible
directly (no GPU): synthetic device identities + 32-byte cache headers
assert that a matching header is accepted while foreign vendor/device,
a bumped UUID (driver update), unknown version, undersized headerSize,
and short/empty blobs are all rejected. Mirrors the GPU-free style of
MemoryTypeFallback / UploadStrategy. Also gitignore the serialized
pipeline_cache.bin a real-device test run drops in the working dir.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
