Initial implementation of jrx - JSX factory for json-render

JSX factory that compiles JSX trees into json-render Spec JSON.
Framework-agnostic custom jsx-runtime, no React dependency at runtime.

- jsx/jsxs/Fragment via jsxImportSource: "jrx"
- render() flattens JrxNode tree into { root, elements, state? } Spec
- Auto key generation (type-N) with explicit key override
- Full feature parity: visible, on, repeat, watch as reserved props
- Function components via component() or plain functions
- @json-render/core as peer dependency

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

src/index.ts

@@ -0,0 +1,3 @@
+export { render } from "./render";
+export { isJrxNode, JRX_NODE, FRAGMENT } from "./types";
+export type { JrxNode, JrxComponent, RenderOptions } from "./types";