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>

example/tsconfig.json

@@ -0,0 +1,23 @@
+{
+  "compilerOptions": {
+    "lib": ["ESNext", "DOM"],
+    "target": "ESNext",
+    "module": "Preserve",
+    "moduleDetection": "force",
+    "jsx": "react-jsx",
+    "allowJs": true,
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "noEmit": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedIndexedAccess": true,
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["./src/*"]
+    }
+  },
+  "exclude": ["dist", "node_modules"]
+}