4wswt4ex2: Add like and unlike for post cards

src/components/FeedView.tsx

@@ -12,6 +12,9 @@ export interface FeedViewProps {
   newCount: number;
   onRetry: () => void;
   onShowNew: () => void;
+  onToggleLike?: (post: CardPost) => void;
+  likeBusy?: ReadonlySet<string>;
+  likeErrors?: ReadonlySet<string>;
   sentinelRef?: Ref<HTMLDivElement>;
   now?: number;
 }
@@ -50,7 +53,14 @@ export function FeedView(p: FeedViewProps) {
       {p.posts.length === 0 ? (
         <p className="feed-message">No posts yet.</p>
       ) : (
-        p.posts.map((post) => <PostCard key={post.key} post={post} now={p.now} />)
+        p.posts.map((post) => <PostCard
+            key={post.key}
+            post={post}
+            now={p.now}
+            onToggleLike={p.onToggleLike}
+            likeBusy={p.likeBusy?.has(post.key)}
+            likeError={p.likeErrors?.has(post.key)}
+          />)
       )}
       {p.loadMoreFailed ? (
         <div className="feed-message" role="alert">