Fix Biome exhaustive-deps error and trim comments

CI's biome ci errored on the scroll effect's [channelId] dependency (not
referenced in the body — it's the re-run trigger). Suppress with the repo's
biome-ignore idiom and cut the added comments down to the essentials.

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

Author: adboio

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

@@ -696,21 +696,15 @@ export function ChannelFeedView({
     return merged;
   }, [tasks, systemMessages]);
 
-  // Open every channel at its latest message. The scroller handles the first
-  // mount itself (defaultScrollPosition), but switching channels only swaps
-  // the rows — no remount — so jump to the bottom before paint whenever the
-  // channel changes. No-ops while the loading state has the viewport unmounted.
   const viewportRef = useRef<HTMLDivElement>(null);
+  // biome-ignore lint/correctness/useExhaustiveDependencies: channelId is the trigger — switching channels swaps the rows without a remount, so re-land at the latest message
   useLayoutEffect(() => {
     const viewport = viewportRef.current;
     if (viewport) viewport.scrollTop = viewport.scrollHeight;
   }, [channelId]);
 
-  // Hold the loading state even when some entries already exist (the "joined"
-  // opener renders as soon as the channel resolves, before the task cards):
-  // mounting the scroller around partial content spends its one-shot initial
-  // end-scroll on a near-empty list, and it never re-scrolls when the real
-  // cards arrive. Pending kickoffs bail out so an optimistic post shows now.
+  // Wait for the complete feed: the scroller's initial end-scroll fires once,
+  // so mounting around partial rows would land it short of the latest message.
   if (isLoading && pending.length === 0) {
     return (
       <div className="flex flex-1 items-center justify-center">

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

@@ -80,10 +80,7 @@ export function WebsiteChannelHome({ channelId }: { channelId: string }) {
   // query is disabled — which reports isLoading:false, indistinguishable from
   // "this channel is empty". useBackendChannel reports loading for the whole
   // identity-resolution window (settling if the resolve fails), so fold it in:
-  // we can't call a channel empty until we know which channel it is. Messages
-  // loading is included so the scroller mounts once with the complete feed and
-  // its one-shot initial end-scroll lands at the latest message (it never
-  // re-fires for late-arriving rows).
+  // we can't call a channel empty until we know which channel it is.
   const isLoading =
     isLoadingChannels ||
     isResolvingChannel ||