docs(nav): note the render-time ref is the intentional latest-value pattern

frontend/src/components/NavigationProvider.tsx

@@ -95,6 +95,9 @@ export function NavigationProvider({ children }: { children: ReactNode }) {
 
   // Refs so the STABLE action callbacks can read the latest state without depending on it — a dep
   // would recreate them on every navigation and re-render every actions consumer (e.g. VideoCard).
+  // Written during render (the sanctioned "latest value" pattern): the ref is only READ in event
+  // handlers after commit, and this provider never suspends or renders in a transition, so no
+  // discarded render can leave it stale.
   const pageRef = useRef(page);
   pageRef.current = page;
   const channelViewRef = useRef(channelView);