v0.3.0

Changed

• make release now verifies that CHANGELOG.md has a ## [X.Y.Z] section for
  the version being released before it bumps, tags, or pushes anything. The
  target version is computed with uv version --dry-run (no mutation), and the
  release aborts early with a helpful message if the entry is missing — so a
  release can no longer be cut with empty auto-generated GitHub Release notes.