FINAL FIX: Docker API URL resolution for internal service communication

- Fixed internal API calls in Docker environment to use port 3000 instead of 9000
- Added DOCKER_ENV detection to properly route internal fetch requests
- Resolves ECONNREFUSED errors when APIs try to call each other within container
- Trade validation now works correctly in Docker: 5 USD position validates properly
- Successfully tested: amountUSD field properly passed through validation pipeline
- Both development and Docker environments now fully functional

app/error.tsx

@@ -0,0 +1,25 @@
+'use client'
+import React from 'react'
+
+export default function Error({
+  error,
+  reset,
+}: {
+  error: Error & { digest?: string }
+  reset: () => void
+}) {
+  return (
+    <div className="min-h-screen bg-gray-900 flex items-center justify-center">
+      <div className="text-center">
+        <h1 className="text-4xl font-bold text-red-400 mb-4">Something went wrong!</h1>
+        <p className="text-gray-400 mb-8">An error occurred while loading this page.</p>
+        <button
+          onClick={reset}
+          className="bg-blue-600 hover:bg-blue-700 text-white font-medium py-3 px-6 rounded-lg transition-colors"
+        >
+          Try again
+        </button>
+      </div>
+    </div>
+  )
+}