perf(frontend): eliminate author profile waterfall — use thought.author directly

thoughts-frontend/app/users/[username]/page.tsx

@@ -126,9 +126,6 @@ export default async function ProfilePage({ params }: ProfilePageProps) {
   const fediverseHandle =
     user.local && apiDomain ? `@${user.username}@${apiDomain}` : null;
 
-  const authorDetails = new Map<string, { avatarUrl?: string | null }>();
-  authorDetails.set(user.username, { avatarUrl: user.avatarUrl });
-
   // Show who the profile owner follows (uses the already-fetched followingResult).
   const friends =
     followingResult.status === "fulfilled"
@@ -277,7 +274,6 @@ export default async function ProfilePage({ params }: ProfilePageProps) {
                 <ThoughtThread
                   key={thought.id}
                   thought={thought}
-                  authorDetails={authorDetails}
                   currentUser={me}
                 />
               ))}