Ghostlink v1.16.1

[1.16.1] - 2026-08-05 (CI fix: release-artifacts.yml release build)

Fixed

• release-artifacts.yml's "Run release validation gates" step runs cd control-plane && go test ./... but never installed a Go toolchain first (unlike ci.yml's Go job, which does). This only surfaced when the v1.16.0 tag push exercised the workflow for real for the first time — it only triggers on push: tags: v*, so no PR check had ever run it. Both matrix legs failed: macos-latest with go: command not found (no Go on that runner image at all), windows-latest with a transient TLS handshake timeout fetching a Go module (plausible without a real setup-go step warming the module cache). Fixed by adding actions/setup-go@v7 with go-version: stable, matching the already-working pattern in ci.yml.
• No functional code changes — this release exists solely to get v1.16.0's actual content (see below) published with working release binaries. v1.16.0 itself published successfully to crates.io; it just never got a GitHub Release with binaries attached.

This patch is cut from the commit immediately after the CI fix landed on main, before later unrelated work (an LLM-shaped benchmarking suite) merged — it carries v1.16.0's code unchanged plus only this workflow fix, not that follow-on feature work.

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