feat(ci): build, smoke-test and release binaries for linux and macOS

[jackmarsh]

Why

Releases are built by hand with release/release.sh on whoever's machine, so darwin_arm64 assets exist only where someone happened to build on a Mac. There's no psql-ai darwin build after 15.x, so postgres_ai_binary(version = "17.6") 404s on Apple Silicon.

What

• .github/workflows/release.yaml builds every version under binaries/ on:

  • ubuntu-24.04 → linux_x86_64. Pinned, not -latest: the binaries link the runner's libicu74 and glibc 2.38, which is what existing consumers already run.
  • macos-14 → darwin_arm64.

  It smoke-tests every tarball and uploads them as artifacts. On a v* tag it publishes one release, only if every build and test passed and the tag matches RELEASE_VERSION. It runs on PRs and on pushes to master too, so a broken build shows up before anyone tags.

• release/smoke_test.sh unpacks a tarball, initdbs, starts postgres, and creates uuid-ossp and pg_stat_statements, plus vector and age (with create_graph) for AI.

• make -j<cores>: a serial 17.6 AI build takes ~16 CPU-minutes, which is too close to the old 20-minute rule timeout on a runner. The timeout is now 60.

• RELEASE_VERSION → v0.0.6, for the first CI-built release.

• README: how to release.

Tested

• Locally on Linux: ./pleasew build //binaries/v17.6/... (1m45s with -j), and both tarballs pass smoke_test.sh.
• smoke_test.sh also passes on the existing v0.0.5 psql-ai-17.6-linux_x86_64 asset.
• The macOS jobs are only tested by this PR's CI run. They show whether AGE and pgvector build on macOS for 16+.

After merge

Tag the release: git tag v0.0.6 && git push origin v0.0.6.

Known gap: the darwin build still links Homebrew icu4c and readline from /opt/homebrew (only libpq's install name is rewritten), so Mac users need them installed. That's out of scope here.

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