fix: correct misleading JSDoc about stubs auto-application

renderWithDefaults only merges plugins and directives, not stubs.
Updated doc to accurately describe behavior.

Addresses review feedback:
https://github.com/Comfy-Org/ComfyUI_frontend/pull/10628#discussion_r3004203297

src/utils/test-utils.ts

@@ -42,10 +42,11 @@ const defaultDirectiveStubs: Record<string, () => void> = {
  *
  * Use via `global.stubs` in render options:
  * ```ts
- * render(MyComponent, { global: { stubs: { Button: stubs.Button } } })
+ * render(MyComponent, { global: { stubs: { Skeleton: stubs.Skeleton } } })
  * ```
  *
- * Or use `renderWithDefaults` which auto-applies these as defaults.
+ * Or use `renderWithDefaults` which provides plugins and directives.
+ * Import `stubs` and pass them via `global.stubs` when needed.
  */
 const SkeletonStub = defineComponent({
   name: 'Skeleton',