feat: add incremental spacetime migration import

scripts/spacetime-migration-common.mjs

@@ -67,6 +67,8 @@ export function parseArgs(argv) {
         .filter(Boolean);
     } else if (arg === '--replace-existing') {
       options.replaceExisting = true;
+    } else if (arg === '--incremental') {
+      options.incremental = true;
     } else if (arg === '--dry-run') {
       options.dryRun = true;
     } else if (arg === '--anonymous' || arg === '--no-config') {