Add example: Bun HTTP server showcasing jrx JSX-to-JSON rendering

Bun React app with HMR that demonstrates jrx's render() pipeline.
Shows JSX source, live UI via @json-render/react, and JSON output
side by side.

- example/specs/simple.tsx: flat Stack > Text + Button
- example/specs/full.tsx: nested layout with state, events,
  visibility conditions, and watchers
- Uses defineCatalog + defineRegistry from @json-render/react
- Fix package.json exports to match actual tsup output (.js/.cjs
  instead of .mjs/.js)

Co-authored-by: Ona <no-reply@ona.com>

package.json

@@ -4,24 +4,24 @@
   "license": "MIT",
   "description": "JSX factory for json-render. Write JSX, get Spec JSON.",
   "type": "module",
-  "main": "./dist/index.js",
-  "module": "./dist/index.mjs",
+  "main": "./dist/index.cjs",
+  "module": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
       "types": "./dist/index.d.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.js"
+      "import": "./dist/index.js",
+      "require": "./dist/index.cjs"
     },
     "./jsx-runtime": {
       "types": "./dist/jsx-runtime.d.ts",
-      "import": "./dist/jsx-runtime.mjs",
-      "require": "./dist/jsx-runtime.js"
+      "import": "./dist/jsx-runtime.js",
+      "require": "./dist/jsx-runtime.cjs"
     },
     "./jsx-dev-runtime": {
       "types": "./dist/jsx-dev-runtime.d.ts",
-      "import": "./dist/jsx-dev-runtime.mjs",
-      "require": "./dist/jsx-dev-runtime.js"
+      "import": "./dist/jsx-dev-runtime.js",
+      "require": "./dist/jsx-dev-runtime.cjs"
     }
   },
   "files": [