feat(release): ship zipped binaries so rokit and mise can install lpm

[ryancundiff]

rokit and mise install a tool from a release archive, not a loose binary, so neither could install lpm at all. Releases now also upload lpm-{os}-{arch}.zip holding a bare lpm[.exe] at its root, and self update reads that instead.

The bare binary keeps being uploaded for now, and that is the whole reason this can ship in one release: every lpm already out there derives lpm-{os}-{arch}[.exe] and matches it exactly, so dropping it would strand those installs on a self update that can never find its asset again. They can reach this version, and from this version on only the zip is read. The bare asset can stop being published once nobody is left on a version that needs it -- nothing current reads it.

Unpacking goes through tools::archive, the same code that unpacks every other tool's release, so lpm now reads its own the way it reads everyone else's. Two things it does not inherit: the binary is looked up by name rather than taken from the archive root, so a nested layout still updates, and a non-archive asset is refused instead of being written through as the executable -- a truncated download or an error page served under the zip's name would otherwise brick the install.

Closes #28