feat(frontend): remote actor lookup and follow from search page

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

@@ -0,0 +1,57 @@
+"use client";
+
+import { useState } from "react";
+import { useAuth } from "@/hooks/use-auth";
+import { followRemoteUser, RemoteActor } from "@/lib/api";
+import { Button } from "@/components/ui/button";
+import { UserAvatar } from "@/components/user-avatar";
+import { toast } from "sonner";
+import { UserPlus } from "lucide-react";
+
+interface RemoteUserCardProps {
+  actor: RemoteActor;
+}
+
+export function RemoteUserCard({ actor }: RemoteUserCardProps) {
+  const [followed, setFollowed] = useState(false);
+  const [loading, setLoading] = useState(false);
+  const { token } = useAuth();
+
+  const handleFollow = async () => {
+    if (!token) {
+      toast.error("You must be logged in to follow users.");
+      return;
+    }
+    setLoading(true);
+    try {
+      await followRemoteUser(actor.handle, token);
+      setFollowed(true);
+      toast.success(`Follow request sent to ${actor.handle}`);
+    } catch {
+      toast.error("Failed to send follow request.");
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <div className="flex items-center justify-between p-4 border rounded-lg">
+      <div className="flex items-center gap-3">
+        <UserAvatar src={actor.avatarUrl} alt={actor.displayName ?? actor.handle} />
+        <div>
+          <p className="font-medium">{actor.displayName ?? actor.handle}</p>
+          <p className="text-sm text-muted-foreground">{actor.handle}</p>
+        </div>
+      </div>
+      <Button
+        onClick={handleFollow}
+        disabled={loading || followed}
+        variant={followed ? "secondary" : "default"}
+        size="sm"
+      >
+        <UserPlus className="mr-2 h-4 w-4" />
+        {followed ? "Requested" : "Follow"}
+      </Button>
+    </div>
+  );
+}