Prefer latest version over best CPU match. An amd64v4 machine gets
v2.0.0 (baseline only) instead of v1.0.0 (which had a v4 build)
because recency beats specificity.
- buildmeta: add amd64v2/v3/v4 micro-levels, ArchFallbacks, LibcFallbacks
- classify: detect micro-arch levels, treat Windows "arm" as ARM64
- platlatest: add Resolve() that walks fallback chains picking newest
classify extracts OS, arch, libc, and format from release asset
filenames using regex pattern matching with priority ordering
(x86_64 before x86, arm64 before armv7, etc.).
platlatest tracks the newest release version per build target
(OS+arch+libc triplet) to handle the common case where Windows
or macOS releases lag behind Linux by several versions.
