Add support for nested manifolds

Introduced the `NestedManifoldRegion` class to enable embedding of `WorkflowFunctionManifold` inside regions, allowing hierarchical workflows. Updated `bin.js` to demonstrate the new functionality and adjusted `lib.js` for nested region navigation and execution logic. Updated `package.json` to specify "type": "module" for ES module support.

package.json

@@ -1,6 +1,7 @@
 {
   "name": "workflow-function-manifold",
   "version": "1.0.2",
+  "type": "module",
   "description": "for building dynamic, LLM-driven workflows using a region-based execution model",
   "main": "index.js",
   "bin": {