Rename package from jrx to jfx

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

example/specs/simple.tsx

@@ -1,10 +1,10 @@
-/** @jsxImportSource jrx */
-import { render } from "jrx";
+/** @jsxImportSource jfx */
+import { render } from "jfx";
 import { Stack, Text, Button } from "../components";
 
 export const simpleSpec = render(
   <Stack>
-    <Text content="Hello from jrx!" />
+    <Text content="Hello from jfx!" />
     <Button label="Click me" />
   </Stack>
 );