fix(frontend): correct proxy path to /api/proxy/api/ for fetch calls

The Next.js proxy at /api/proxy/[...path] forwards the path to
AGPT_SERVER_URL which already includes /api. So the path needs
/api/proxy/api/... (double api — one for proxy route, one for backend).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

autogpt_platform/frontend/src/app/(platform)/admin/rate-limits/components/useRateLimitManager.ts

@@ -86,7 +86,7 @@ export function useRateLimitManager() {
 
     try {
       const response = await fetch(
-        `/api/proxy/copilot/admin/rate_limit/search_users?query=${encodeURIComponent(trimmed)}&limit=20`,
+        `/api/proxy/api/copilot/admin/rate_limit/search_users?query=${encodeURIComponent(trimmed)}&limit=20`,
       );
       if (!response.ok) {
         throw new Error("Failed to search users");
@@ -181,7 +181,7 @@ export function useRateLimitManager() {
   async function handleTierChange(newTier: string) {
     if (!rateLimitData) return;
 
-    const response = await fetch("/api/proxy/copilot/admin/rate_limit/tier", {
+    const response = await fetch("/api/proxy/api/copilot/admin/rate_limit/tier", {
       method: "POST",
       headers: { "Content-Type": "application/json" },
       body: JSON.stringify({