fix(decorators): Add Symbol.metadata polyfill and import it at entry to ensure decorator metadata is available

ts/index.ts

@@ -1,3 +1,6 @@
+// Polyfill must be imported first - ES modules hoist exports before code runs
+import './shim.js';
+
 export * from './classes.db.js';
 export * from './classes.collection.js';
 export * from './classes.doc.js';