Key the feed scroller by channel so revisits land at the latest message

Channel-to-channel navigation swaps the feed content without a route
remount, so the scroller provider persisted and its one-shot
defaultScrollPosition never re-applied — a revisited channel kept the
previous channel's scroll offset (often the top). Keying the provider by
channelId fresh-mounts it per channel, re-firing the initial end-scroll.

Generated-By: PostHog Code
Task-Id: d887d524-7d87-4d7a-b38c-b20289937ad1

Author: adboio

packages/ui/src/features/canvas/components/ChannelFeedView.tsx

@@ -716,7 +716,11 @@ export function ChannelFeedView({
   const latestPendingId = pending[pending.length - 1]?.id;
 
   return (
-    <ChatMessageScrollerProvider defaultScrollPosition="end">
+    // Keyed by channel: switching channels swaps the content without a route
+    // remount, but the scroller only applies defaultScrollPosition once per
+    // mount — an un-keyed provider would keep the previous channel's scroll
+    // offset instead of landing at the latest message.
+    <ChatMessageScrollerProvider key={channelId} defaultScrollPosition="end">
       <FollowOwnPost latestPendingId={latestPendingId} />
       <ChatMessageScroller className="min-h-0 flex-1">
         <ChatMessageScrollerViewport>