fix(frontend): fix lint and type errors in tier selector

- Replace template literal with regular string for static URL
- Fix TypeScript cast via intermediate `unknown` for tier field

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

autogpt_platform/frontend/src/app/(platform)/admin/rate-limits/components/RateLimitDisplay.tsx

@@ -42,7 +42,8 @@ export function RateLimitDisplay({
   const [isChangingTier, setIsChangingTier] = useState(false);
   const { toast } = useToast();
 
-  const currentTier = ((data as Record<string, unknown>).tier as Tier) ?? "PRO";
+  const currentTier =
+    ((data as unknown as Record<string, unknown>).tier as Tier) ?? "PRO";
 
   async function handleReset() {
     const msg = resetWeekly

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

@@ -202,17 +202,14 @@ export function useRateLimitManager() {
   async function handleTierChange(newTier: string) {
     if (!rateLimitData) return;
 
-    const response = await fetch(
-      `/api/copilot/admin/rate_limit/tier`,
-      {
-        method: "POST",
-        headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({
-          user_id: rateLimitData.user_id,
-          tier: newTier,
-        }),
-      },
-    );
+    const response = await fetch("/api/copilot/admin/rate_limit/tier", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({
+        user_id: rateLimitData.user_id,
+        tier: newTier,
+      }),
+    });
 
     if (!response.ok) {
       throw new Error("Failed to update tier");