Release: automate Homebrew tap and Scoop bucket updates

[DIST-PATH-INSTALL] in docs/specs/DISTRIBUTION-SPEC.md tells users to install with:

• brew install nimblesite/tap/sharplsp
• scoop install nimblesite/sharplsp

Nothing in release.yml pushes to Nimblesite/homebrew-tap or Nimblesite/scoop-bucket, so those commands only work for whatever version someone last updated by hand. docs/plans/DISTRIBUTION-PLAN.md had this ticked as done; it has been corrected to [ ] NOT BUILT.

The blocker is now gone: every release publishes per-platform standalone server archives (sharplsp-<platform>.tar.gz / .zip) plus a SHA256SUMS covering them, which is exactly what a formula and a manifest need.

Remaining work:

• Create/confirm the Nimblesite/homebrew-tap and Nimblesite/scoop-bucket repos
• Provision a token (or GitHub App) with write access to both, scoped to the release environment alongside the existing publish secrets ([DIST-SECRETS])
• Add a publish-packages job to release.yml, needing release, that rewrites the formula/manifest URL + sha256 from the release assets and pushes
• Skip the push for prerelease (hyphenated) tags, matching how publish-marketplace handles --pre-release
• Update [DIST-PATH-INSTALL] to drop the "Not yet automated" note once it lands

Start by reading release.yml, especially publish-marketplace, and the [DIST-PATH-INSTALL] and [DIST-SECRETS] sections referenced in docs/specs/DISTRIBUTION-SPEC.md and docs/plans/DISTRIBUTION-PLAN.md. Confirm the release archives and SHA256SUMS inputs, then verify that stable releases update both the Homebrew formula and Scoop manifest while prerelease tags do not, and that the documentation no longer says automation is pending.