Fix: use INTERNAL_API_URL for runtime backend URL (NEXT_PUBLIC_ is baked at build time)

src/app/api/[...route]/route.ts

@@ -27,8 +27,9 @@ async function handleProxy(req: NextRequest, { params }: { params: Promise<{ rou
     
     const url = new URL(req.url);
     
-    // Force ALL traffic to go through our own Centralized Proxy Server (Express Backend)
-    const localBase = process.env.NEXT_PUBLIC_API_URL || 'http://127.0.0.1:3001';
+    // INTERNAL_API_URL is read at RUNTIME (not baked at build time like NEXT_PUBLIC_*)
+    // This allows Docker Swarm / Portainer to set the backend URL dynamically
+    const localBase = process.env.INTERNAL_API_URL || process.env.NEXT_PUBLIC_API_URL || 'http://127.0.0.1:3001';
     const destinationUrl = `${localBase}/api/${route}${url.search}`;
     
     // Prepare headers