build, produce musl-static Linux binary for universal glibc compatibility

[steven-varga]

Produce a fully static Linux binary using musl libc to eliminate glibc version dependencies. Currently binaries built on Ubuntu 24.04 fail on older systems (GLIBC_2.36/2.38 not found).

Acceptance Criteria

• Alpine-based CI job builds h5cpp-compiler with musl
• Binary is fully static (no dynamic libc dependency)
• Packaged as .tar.gz in GitHub Releases
• Smoke-tested on Ubuntu 20.04 container