Document why the render wrapper and setup import exist in render.tsx

Add explicit comments explaining that tests must import from this module
(not directly from @testing-library/react) to ensure the ./setup
side-effects run first: ResizeObserver polyfill, Event/CustomEvent
alignment with jsdom, and afterEach(cleanup) registration.

Author: sergiou87

app/test/helpers/ui/render.tsx

@@ -1,5 +1,12 @@
 import * as React from 'react'
+
+// This import MUST stay here — it runs side-effects that every UI test needs:
+// polyfilling ResizeObserver, aligning globalThis.Event/CustomEvent with jsdom,
+// and registering an afterEach(cleanup) hook. Tests should never import
+// '@testing-library/react' directly; they should import from this module
+// instead so these side-effects are guaranteed to run first.
 import './setup'
+
 import {
   fireEvent,
   render as rtlRender,
@@ -11,6 +18,14 @@ import {
 
 type UIErrorRenderOptions = Omit<RenderOptions, 'queries'>
 
+/**
+ * Thin wrapper around Testing Library's render.
+ *
+ * This exists so that every test imports from this module rather than directly
+ * from '@testing-library/react'. Importing from here guarantees the './setup'
+ * side-effects (ResizeObserver polyfill, Event/CustomEvent alignment, and
+ * afterEach cleanup) have already executed before any component is rendered.
+ */
 export function render(
   element: React.ReactElement,
   options?: UIErrorRenderOptions