fix: resolve Next.js rendering errors, hook unhandled fetch error, theme logo layout, double header, and FastAPI multipart dependency

src/hooks/useActiveUser.ts

@@ -44,7 +44,10 @@ export function useActiveUser() {
     try {
       const res = await fetch(`/api/users/${id}`);
       if (!res.ok) {
-        throw new Error("Failed to fetch user profile");
+        console.error("Failed to fetch user profile, status:", res.status);
+        setError("Failed to fetch user profile");
+        setUser(null);
+        return;
       }
       const data = await res.json();
       setUser(data);