fix(release): gitignore dist-darwin/ so goreleaser sees a clean tree

[zzet]

Problem

The v0.53.0 release job failed (run 28288459792) with:

⨯ release failed after 0s
  error= git is in a dirty state
  Please check in your pipeline what can be changing the following files:
  ?? dist-darwin/

The native-darwin work added in #178 stages the macOS archives in dist-darwin/ (downloaded as an artifact) before running goreleaser release --clean. goreleaser refuses to run on a dirty work tree, and the untracked dist-darwin/ tripped that check, so goreleaser aborted before creating the release — no v0.53.0 artifacts were published.

Fix

dist/ (goreleaser's own output) was already in .gitignore for exactly this reason; dist-darwin/ was simply missed. Ignore it too:

# Release: native-darwin archives the release job stages outside dist/ (which
# --clean wipes). Must be ignored or goreleaser aborts on a dirty work tree.
dist-darwin/

Verification

With dist-darwin/ populated, git status --porcelain (what goreleaser's dirty check reads) no longer reports it; git status --porcelain --ignored confirms the rule matches (!! dist-darwin/). This fixes future releases, matching #178's note about the release path.

Follow-up

The v0.53.0 tag produced no release artifacts (goreleaser aborted). After this merges, re-cut the tag (delete + re-push v0.53.0, or bump to v0.53.1) to actually publish the release.