docs: update to next 15 + eslint 9 (#9839)

* update next

* updated react

* update eslint

* finish updating eslint

* fix content lint errors

* fix docs test

* fix vale action

* fix installation errors

www/apps/api-reference/markdown/client-libraries.mdx

@@ -0,0 +1,25 @@
+import { H3 } from "docs-ui"
+import Space from "@/components/Space"
+import DownloadFull from "@/components/DownloadFull"
+
+<H3 className="!mt-0">Just Getting Started?</H3>
+
+Check out the [Medusa v2 Documentation](https://docs.medusajs.com).
+
+<Space bottom={8} />
+
+<H3 className="!mt-0">Medusa JS SDK</H3>
+
+To use Medusa's JS SDK library, install the following packages in your project (not required for admin customizations):
+
+```bash
+npm install @medusajs/js-sdk@latest @medusajs/types@latest
+```
+
+Learn more about the JS SDK in [this documentation](https://docs.medusajs.com/resources/js-sdk).
+
+### Download Full Reference
+
+Download this reference as an OpenApi YAML file. You can import this file to tools like Postman and start sending requests directly to your Medusa application.
+
+<DownloadFull />