Imports

Preserve Sage source files

Each upload should create a `Sage Import Batch` and immutable `Sage Raw Row` trace records before normalized lookup records are derived.

Supported first-pass sources General Ledger, Trial Balance, AR invoices, AP bills, inventory, fixed assets, customers, suppliers, items, accounts.

Lock rule Locked batches should not be modified. Corrections should be imported as a new batch.

Traceability Keep original file name, source type, uploaded file, row number, and raw payload for every row.

Company scope No accounting import should proceed unless `sage_company` is present.