Add a public numbering module and route fragmenting, validation,
and scaffold preparation through the canonical numbering entry.
Rewrite the repository entry docs around the fixed numbering
contract, add MkDocs landing pages, and document the mirror
mapping used for medicinal-chemistry comparisons.
Also refresh the validation analysis reports to explain the
canonical-versus-mirrored numbering relationship.
- skip fused/shared/multi-anchor side systems during extraction
- add fragment library schema and fragment_library.csv export
- make scaffold prep strict for non-spliceable positions
Unify macrolactone detection, numbering, fragmentation, and
splicing under the installable macro_lactone_toolkit package.
- replace legacy src.* modules with the new package layout
- add analyze/number/fragment CLI entrypoints and pixi tasks
- migrate tests, README, and scripts to the new package API
