BREAKING CHANGE(Smartjson): Require TC39 Stage 3 decorators for @foldDec (use accessor), switch foldDec to initializer-based implementation, improve buffer encode/decode handling, bump dependencies and update docs/tests.

ts/index.ts

@@ -207,14 +207,23 @@ export class Smartjson {
 }
 
 /**
- * Decorator that marks a property as foldable
+ * Decorator that marks a property as foldable (TC39 Stage 3 decorator)
+ * Use with the `accessor` keyword: @foldDec() accessor myProp: string;
  */
 export const foldDec = () => {
-  return (target: any, key: string) => {
-    if (!target.saveableProperties) {
-      target.saveableProperties = [];
-    }
-    target.saveableProperties.push(key);
+  return <This extends Smartjson, Value>(
+    _value: ClassAccessorDecoratorTarget<This, Value>,
+    context: ClassAccessorDecoratorContext<This, Value>
+  ): ClassAccessorDecoratorResult<This, Value> | void => {
+    const propertyName = String(context.name);
+    context.addInitializer(function (this: This) {
+      if (!this.saveableProperties) {
+        this.saveableProperties = [];
+      }
+      if (!this.saveableProperties.includes(propertyName)) {
+        this.saveableProperties.push(propertyName);
+      }
+    });
   };
 };