- Switch FUSION_MODEL to fusion.followup.engine so adapter mode
selection matches the new module
- Add list_overdue() with fusion/enterprise/community variants
- Re-route send_followup_via_fusion to engine.send_followup_email
- 4 new TransactionCase tests (73 total)
Existing aging / overdue_invoices adapter methods continue to fall
back to the community implementation.
Made-with: Cursor