fix(frontend): forward X-API-Key header through proxy (#11530)

The Next.js API proxy was stripping the X-API-Key header when forwarding
requests to the backend, causing API key authentication to fail in
environments where requests go through the proxy (e.g., dev
environment).

### Changes 🏗️

- Updated `createRequestHeaders()` in
`frontend/src/lib/autogpt-server-api/helpers.ts` to forward the
`X-API-Key` header from the original request to the backend

### Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
- [x] Verify API key authentication works when requests go through the
Next.js proxy
- [x] Verify existing authentication (Authorization header) still works
  - [x] Verify admin impersonation header forwarding still works

#### For configuration changes:

- [x] `.env.default` is updated or already compatible with my changes
- [x] `docker-compose.yml` is updated or already compatible with my
changes
- [x] I have included a list of my configuration changes in the PR
description (under **Changes**)

No configuration changes required.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude <noreply@anthropic.com>

autogpt_platform/frontend/src/lib/autogpt-server-api/helpers.ts

@@ -1,4 +1,7 @@
-import { IMPERSONATION_HEADER_NAME } from "@/lib/constants";
+import {
+  API_KEY_HEADER_NAME,
+  IMPERSONATION_HEADER_NAME,
+} from "@/lib/constants";
 import { getServerSupabase } from "@/lib/supabase/server/getServerSupabase";
 import { environment } from "@/services/environment";
 import { Key, storage } from "@/services/storage/local-storage";
@@ -154,6 +157,12 @@ export function createRequestHeaders(
     if (impersonationHeader) {
       headers[IMPERSONATION_HEADER_NAME] = impersonationHeader;
     }
+
+    // Forward X-API-Key header if present
+    const apiKeyHeader = originalRequest.headers.get(API_KEY_HEADER_NAME);
+    if (apiKeyHeader) {
+      headers[API_KEY_HEADER_NAME] = apiKeyHeader;
+    }
   }
 
   return headers;

autogpt_platform/frontend/src/lib/constants.ts

@@ -5,3 +5,6 @@
 // Admin impersonation
 export const IMPERSONATION_HEADER_NAME = "X-Act-As-User-Id";
 export const IMPERSONATION_STORAGE_KEY = "admin-impersonate-user-id";
+
+// API key authentication
+export const API_KEY_HEADER_NAME = "X-API-Key";