- add source.cherry_pick (and cherry-pick alias) to package spec parsing/serialization
- apply listed cherry-picks in order after git checkout
- reject cherry_pick on non-git sources with explicit error
- include cherry_pick in interactive spec TOML output
- add parsing/behavior tests and update Source test fixtures
- add BuildType::Meta handling in builder and interactive spec output
- allow metapackage specs without sources and expose is_metapackage()
- avoid build deps in install planning for metapackages
- run custom non-function build.sh scripts with `sh -e` to stop on first failure
- add regression test for custom script fail-fast behavior
- apply small cleanup refactors (let-chains/iterator simplifications)
SFG545