fix: clean up onboarding tour timer leaks

Fix two timer cleanup bugs in onboarding-tour.tsx:

1. Remove cleanup return from useCallback (only works in useEffect).
   Clear retryTimerRef at the start of updateTarget and in a
   dedicated useEffect cleanup instead.

2. Track recursive setTimeout calls via startCheckTimerRef so they
   are properly cancelled on unmount instead of leaking.

Fixes #1091

surfsense_web/components/onboarding-tour.tsx

@@ -429,6 +429,7 @@ export function OnboardingTour() {
 	const pathname = usePathname();
 	const retryCountRef = useRef(0);
 	const retryTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+	const startCheckTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 	const maxRetries = 10;
 	// Track previous user ID to detect user changes
 	const previousUserIdRef = useRef<string | null>(null);
@@ -460,6 +461,7 @@ export function OnboardingTour() {
 
 	// Find and track target element with retry logic
 	const updateTarget = useCallback(() => {
+		if (retryTimerRef.current) clearTimeout(retryTimerRef.current);
 		if (!currentStep) return;
 
 		const el = document.querySelector(currentStep.target);
@@ -480,11 +482,13 @@ export function OnboardingTour() {
 				}
 			}, 200);
 		}
+	}, [currentStep]);
 
+	useEffect(() => {
 		return () => {
 			if (retryTimerRef.current) clearTimeout(retryTimerRef.current);
 		};
-	}, [currentStep]);
+	}, []);
 
 	// Check if tour should run: localStorage + data validation with user ID tracking
 	useEffect(() => {
@@ -573,15 +577,15 @@ export function OnboardingTour() {
 				setPosition(calculatePosition(connectorEl, TOUR_STEPS[0].placement));
 			} else {
 				// Retry after delay
-				setTimeout(checkAndStartTour, 200);
+				startCheckTimerRef.current = setTimeout(checkAndStartTour, 200);
 			}
 		};
 
 		// Start checking after initial delay
-		const timer = setTimeout(checkAndStartTour, 500);
+		startCheckTimerRef.current = setTimeout(checkAndStartTour, 500);
 		return () => {
 			cancelled = true;
-			clearTimeout(timer);
+			if (startCheckTimerRef.current) clearTimeout(startCheckTimerRef.current);
 		};
 	}, [mounted, user?.id, searchSpaceId, pathname, threadsData, documentTypeCounts, connectors]);