fix: React 19 JSX imports (#1879)

## 📝 Changes

- fixes incompatible JSX runtime included in the build by marking it as
external: `react/jsx-runtime`

Author: stephenjwatkins

.changeset/red-ties-float.md

@@ -0,0 +1,5 @@
+---
+"@easypost/easy-ui": patch
+---
+
+fix: React 19 JSX runtime import

easy-ui-react/vite.config.mts

@@ -51,7 +51,10 @@ export default defineConfig({
       cssFileName: "style",
     },
     rollupOptions: {
-      external: ["react", "react-dom"],
+      external: (id) =>
+        ["react", "react-dom"].some(
+          (pkg) => id === pkg || id.startsWith(`${pkg}/`),
+        ),
       output: [
         {
           format: "cjs",