fix(frontend): remove dead activeTab state; guard URL hostname parse

thoughts-frontend/components/remote-user-profile/profile-card.tsx

@@ -12,6 +12,13 @@ interface ProfileCardProps {
 }
 
 export function ProfileCard({ actor, action }: ProfileCardProps) {
+  let hostname: string | null = null;
+  try {
+    if (actor.url) hostname = new URL(actor.url).hostname;
+  } catch {
+    hostname = actor.url;
+  }
+
   return (
     <>
       <div className="flex justify-between items-start">
@@ -47,7 +54,7 @@ export function ProfileCard({ actor, action }: ProfileCardProps) {
           className="flex items-center overflow-hidden"
         >
           <ExternalLink className="mr-2 h-4 w-4 shrink-0" />
-          <span className="truncate">{new URL(actor.url).hostname}</span>
+          <span className="truncate">{hostname}</span>
         </Link>
       </Button>