Native shard merge drops the v0.30.0 macOS Mint binary

Follow-up to #1029.

`release/scripts/merge-release-native-platform-shards.py` removes `mint-{tag}-macos-arm64` from the roster at `>= (0, 30, 0)`. `merge-release-binary-shards.py` and `registry-release` stop listing Mint only after 0.30.0 (`> (0, 30, 0)`). v0.30.0 shipped `mint-v0.30.0-macos-arm64`, so re-merging its native shards with current tooling would omit that asset.

- [ ] Use `> (0, 30, 0)` in the native script
- [ ] Add a 0.30.0 case to `release/scripts/test_release_native_platform.py`

Also cover historical image onboarding (Codex thread PRRT_kwDOTEV0gs6h2oGw): the current v0.30.0 image roster retains Mint, but current-tree onboarding validation expects its retired Dockerfile, staging recipe and advisory baseline. Historical versions need inputs resolved from their versioned source instead of requiring retired Mint build inputs on current main.

- [ ] Verify v0.30.0 image onboarding against its historical source inputs.
- [ ] Keep current-version Mint retirement intact and preserve historical manifests and the VERIFY roster.

Start with release/scripts/merge-release-native-platform-shards.py and release/scripts/test_release_native_platform.py, comparing the v0.30.0 conditions with merge-release-binary-shards.py and registry-release. Then trace image onboarding validation and its historical source inputs. Done means v0.30.0 retains the macOS Mint binary and image manifests and VERIFY remain valid, while current-version Mint retirement is unchanged.

Written by the indexing model from the issue text.