fix: add AbortController and unmount guard to useIpLookup hook

- Add AbortController to cancel pending IP lookups when component unmounts
- Prevent state updates on unmounted components by checking abort signal before setState calls
- Add useEffect cleanup that aborts pending requests on unmount
- Update lookupIp API function to accept optional AbortSignal parameter
- Converts callback-based fetch to async/await pattern for better control flow
- Aligns with other API functions that already support abort signals (fetchJails, fetchJailBannedIps)

Fixes TASK-ABORT-04

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/api/jails.ts

@@ -237,11 +237,12 @@ export async function unbanAllBans(): Promise<UnbanAllResponse> {
  * Look up ban status and geo-location for an IP address.
  *
  * @param ip - IP address to look up.
+ * @param signal - Optional abort signal for request cancellation.
  * @returns An {@link IpLookupResponse} with ban history and geo info.
  * @throws {ApiError} On non-2xx responses (400 for invalid IP).
  */
-export async function lookupIp(ip: string): Promise<IpLookupResponse> {
-  return get<IpLookupResponse>(ENDPOINTS.geoLookup(ip));
+export async function lookupIp(ip: string, signal?: AbortSignal): Promise<IpLookupResponse> {
+  return get<IpLookupResponse>(ENDPOINTS.geoLookup(ip), signal);
 }
 
 // ---------------------------------------------------------------------------

frontend/src/hooks/useIpLookup.ts

@@ -2,7 +2,7 @@
  * React hook for looking up a single IP address.
  */
 
-import { useCallback, useState } from "react";
+import { useCallback, useEffect, useRef, useState } from "react";
 import { handleFetchError } from "../utils/fetchError";
 import { lookupIp } from "../api/jails";
 import type { IpLookupResponse } from "../types/jail";
@@ -22,22 +22,34 @@ export function useIpLookup(): UseIpLookupResult {
   const [result, setResult] = useState<IpLookupResponse | null>(null);
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
+  const abortRef = useRef<AbortController | null>(null);
 
-  const lookup = useCallback((ip: string) => {
-    setLoading(true);
-    setError(null);
-    setResult(null);
+  const lookup = useCallback((ip: string): void => {
+    (async (): Promise<void> => {
+      // Abort any previous lookup
+      abortRef.current?.abort();
+      const ctrl = new AbortController();
+      abortRef.current = ctrl;
 
-    lookupIp(ip)
-      .then((res) => {
+      setLoading(true);
+      setError(null);
+      setResult(null);
+
+      try {
+        const res = await lookupIp(ip, ctrl.signal);
+        if (ctrl.signal.aborted) return;
         setResult(res);
-      })
-      .catch((err: unknown) => {
+      } catch (err: unknown) {
+        if (ctrl.signal.aborted) return;
         handleFetchError(err, setError, "Failed to lookup IP");
-      })
-      .finally(() => {
-        setLoading(false);
-      });
+      } finally {
+        if (!ctrl.signal.aborted) {
+          setLoading(false);
+        }
+      }
+    })().catch(() => {
+      // Silently ignore abort errors
+    });
   }, []);
 
   const clear = useCallback(() => {
@@ -45,5 +57,12 @@ export function useIpLookup(): UseIpLookupResult {
     setError(null);
   }, []);
 
+  // Cleanup: abort any pending lookup on unmount
+  useEffect(() => {
+    return (): void => {
+      abortRef.current?.abort();
+    };
+  }, []);
+
   return { result, loading, error, lookup, clear };
 }