Fix stale refresh usage in QueryInsightsPage effect hooks

Replaced `refresh` with `useRef` to ensure the latest value is always used in async operations. Added cleanup logic to handle component unmounts during API calls, preventing state updates on unmounted components.

frontend/src/pages/QueryInsightsPage.jsx

@@ -1,4 +1,4 @@
-import React, { useEffect, useState } from "react";
+import React, { useEffect, useRef, useState } from "react";
 import { apiFetch } from "../api";
 import { useAuth } from "../state";
 
@@ -62,6 +62,7 @@ function buildQueryTips(row) {
 
 export function QueryInsightsPage() {
   const { tokens, refresh } = useAuth();
+  const refreshRef = useRef(refresh);
   const [targets, setTargets] = useState([]);
   const [targetId, setTargetId] = useState("");
   const [rows, setRows] = useState([]);
@@ -71,6 +72,10 @@ export function QueryInsightsPage() {
   const [error, setError] = useState("");
   const [loading, setLoading] = useState(true);
 
+  useEffect(() => {
+    refreshRef.current = refresh;
+  }, [refresh]);
+
   useEffect(() => {
     (async () => {
       try {
@@ -89,17 +94,26 @@ export function QueryInsightsPage() {
 
   useEffect(() => {
     if (!targetId) return;
+    let active = true;
     (async () => {
       try {
-        const data = await apiFetch(`/targets/${targetId}/top-queries`, {}, tokens, refresh);
+        const data = await apiFetch(`/targets/${targetId}/top-queries`, {}, tokens, refreshRef.current);
+        if (!active) return;
         setRows(data);
-        setSelectedQuery(data[0] || null);
-        setPage(1);
+        setSelectedQuery((prev) => {
+          if (!prev) return data[0] || null;
+          const keep = data.find((row) => row.queryid === prev.queryid);
+          return keep || data[0] || null;
+        });
+        setPage((prev) => (prev === 1 ? prev : 1));
       } catch (e) {
-        setError(String(e.message || e));
+        if (active) setError(String(e.message || e));
       }
     })();
-  }, [targetId, tokens, refresh]);
+    return () => {
+      active = false;
+    };
+  }, [targetId, tokens?.accessToken, tokens?.refreshToken]);
 
   const dedupedByQueryId = [...rows].reduce((acc, row) => {
     if (!row?.queryid) return acc;