fix: resolve WebUI API proxy ECONNREFUSED and configmap placeholder issues

- Fix route handlers to use API_GATEWAY_URL env var with correct K8s fallback
  instead of localhost:3015
- Replace ${} placeholders in configmap.yaml with actual static values to
  prevent kustomize from overwriting envsubst-generated config
- Separate secrets into dedicated secrets.yaml for envsubst processing
- Update deploy.sh to only envsubst secrets (configmap now has static values)

Made-with: Cursor

backend/webui/src/app/api/chat/route.ts

@@ -1,34 +1,41 @@
 import { NextRequest, NextResponse } from 'next/server';
 
-const API_URL = process.env.API_URL || 'http://localhost:3015';
+const API_GATEWAY =
+  process.env.API_GATEWAY_URL ||
+  process.env.API_URL ||
+  'http://api-gateway:3015';
 
 export async function POST(request: NextRequest): Promise<NextResponse> {
-  const targetUrl = `${API_URL}/api/chat`;
+  const targetUrl = `${API_GATEWAY}/api/chat`;
 
   const headers = new Headers();
-  
+
   const authHeader = request.headers.get('authorization');
   if (authHeader) {
     headers.set('Authorization', authHeader);
   }
-  
+
   headers.set('Content-Type', 'application/json');
   headers.set('Accept', 'application/x-ndjson');
 
   try {
     const body = await request.text();
-    
+
     const response = await fetch(targetUrl, {
       method: 'POST',
       headers,
       body,
     });
 
-    const contentType = response.headers.get('content-type') || 'application/x-ndjson';
-    
+    const contentType =
+      response.headers.get('content-type') || 'application/x-ndjson';
+
     const stream = response.body;
     if (!stream) {
-      return NextResponse.json({ error: 'No response body' }, { status: 500 });
+      return NextResponse.json(
+        { error: 'No response body' },
+        { status: 500 },
+      );
     }
 
     return new NextResponse(stream, {
@@ -44,7 +51,7 @@ export async function POST(request: NextRequest): Promise<NextResponse> {
     console.error('[Chat API Proxy] Error:', error);
     return NextResponse.json(
       { error: 'Service unavailable' },
-      { status: 503 }
+      { status: 503 },
     );
   }
 }

backend/webui/src/app/api/v1/[...path]/route.ts

@@ -1,6 +1,9 @@
 import { NextRequest, NextResponse } from 'next/server';
 
-const API_URL = process.env.API_URL || 'http://localhost:3015';
+const API_URL =
+  process.env.API_GATEWAY_URL ||
+  process.env.API_URL ||
+  'http://api-gateway:3015';
 
 async function proxyRequest(
   request: NextRequest,