feat(smartmigration): add initial smartmigration package with MongoDB and S3 migration runner

ts/index.ts

@@ -0,0 +1,21 @@
+/**
+ * @push.rocks/smartmigration — unified migration runner for MongoDB and S3.
+ */
+
+export { SmartMigration, SmartMigrationError } from './classes.smartmigration.js';
+export { MigrationStepBuilder } from './classes.migrationstep.js';
+export { VersionResolver } from './classes.versionresolver.js';
+
+export type {
+  ISmartMigrationOptions,
+  IMigrationContext,
+  IMigrationCheckpoint,
+  IMigrationStepInfo,
+  IMigrationStepDefinition,
+  IMigrationStepResult,
+  IMigrationLedgerEntry,
+  IMigrationRunResult,
+  ISmartMigrationLedgerData,
+} from './interfaces.js';
+
+export type { TMigrationStatus, TLedgerBackend } from './types.js';