add migration

ts/database/migrations/migration-001-initial.ts

@@ -0,0 +1,12 @@
+import { BaseMigration } from './base-migration.ts';
+import type { TQueryFunction } from '../types.ts';
+
+export class Migration001Initial extends BaseMigration {
+  readonly version = 1;
+  readonly description = 'Initial schema';
+
+  up(_query: TQueryFunction): void {
+    // Initial schema is created by createTables() in the database class.
+    // This migration just marks the initial version.
+  }
+}