Chore: set up cargo-dist for releases

[jakobhellermann]

Summary

Sets up cargo-dist so that pushing a vX.Y.Z tag automatically builds release artifacts and publishes them.

• dist-workspace.toml and [package.metadata.dist] in Cargo.toml configure the build.
• .github/workflows/release.yml (regenerated by dist generate) runs the build/publish on tag push.
• Targets: aarch64-apple-darwin, {aarch64,x86_64}-unknown-linux-gnu, x86_64-unknown-linux-musl, x86_64-pc-windows-msvc.
• Installers: Homebrew (publishes to davidborzek/homebrew-tap) and Windows MSI.
• README gained a short "Releasing" section.

Required setup before merging

See cargo-dist Homebrew docs for details.

• Create the tap repo davidborzek/homebrew-tap (empty repo is fine).
• Add a HOMEBREW_TAP_TOKEN repo secret on davidborzek/ringo — a PAT with repo scope on the tap.

Test plan

• cargo build clean
• After merge: push a test tag (e.g. v0.7.2-rc1) to verify the workflow end-to-end before doing a real release.