chore: document new default Vite server.fs.strict behavior

documentation/faq/90-fs-strict.md

@@ -0,0 +1,10 @@
+---
+question: "Internal server error: The request url [...] is outside of Vite serving allow list"
+---
+
+For security reasons, Vite has been configured to only allow filesystem access when the request file fulfils one of these requirements:
+- Within workspace root
+- Within the listed `server.fs.allow` exceptions
+- Part of the dependency graph of your application code
+
+Refer to Vite documentation for [`server.fs.allow`](https://vitejs.dev/config/#server-fs-allow) for configuration and more details.