Fix Admin test upload API endpoint URL & fix AI coach infinite reload caused by session polling

src/hooks/useActiveUser.ts

@@ -41,8 +41,8 @@ export function useActiveUser() {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
 
-  const fetchUserProfile = useCallback(async (id: string) => {
-    setLoading(true);
+  const fetchUserProfile = useCallback(async (id: string, isPoll: boolean = false) => {
+    if (!isPoll) setLoading(true);
     setError(null);
     try {
       const res = await fetch(`/api/users/${id}`);
@@ -71,7 +71,7 @@ export function useActiveUser() {
       console.error("Error fetching active user profile:", err);
       setError(err.message || "Failed to load user");
     } finally {
-      setLoading(false);
+      if (!isPoll) setLoading(false);
     }
   }, []);
 
@@ -90,7 +90,7 @@ export function useActiveUser() {
     
     // Poll every 10 seconds for session validity
     const interval = setInterval(() => {
-      fetchUserProfile(userId);
+      fetchUserProfile(userId, true);
     }, 10000);
     
     return () => {