saveMapMigrationFolderDecisions
Batch-save the Decide & Map draft — the ONLY writer of folder decision state (parity with saveMapMigrationRoleDecisions). The step stages every drag/clear in memory and flushes the whole draft here in one transaction, right before it starts the push run. Nothing is written per-edit (STEP_DESIGN_BRIEF §9).
saveMapMigrationFolderDecisions(
decisions: [MapMigrationFolderDecisionInput!]!
): MapMigrationAffectedCount!
