docs(release): document native Linux packages

[jmgilman]

Summary

• pin all consumer documentation and the copyable workflow to verified release v0.1.2
• add nFPM DEB, RPM, and APK configuration plus package metadata to the copyable Go example
• document the 26-file release contract, native package verification, direct installation, and unsigned-package limitation

Verification

• v0.1.2 Release workflow completed all four jobs successfully
• all 24 checksummed v0.1.2 payloads passed SHA-256, Cosign identity, and GitHub attestation verification
• all six published packages installed and ran on Ubuntu 24.04, Fedora 43, and Alpine 3.22 for amd64 and arm64
• mise exec -- goreleaser check in examples/go-release
• mise exec -- goreleaser release --snapshot --clean --skip=sign in examples/go-release
• generated example DEB, RPM, and APK installed and ran on their native amd64 distributions
• mise exec -- moon run check
• git diff --check