feat(frontend): per-user DLOB source header

- Add cookie-based source selector (mevnode|drift)\n- Proxy sets x-hasura-dlob-source for HTTP + WS\n- Include same proxy script mount in prod overlay

kustomize/overlays/prod/kustomization.yaml

@@ -6,5 +6,16 @@ namespace: trade-prod
 resources:
   - ../../base
 
+patchesStrategicMerge:
+  - frontend-graphql-proxy-patch.yaml
+
+configMapGenerator:
+  - name: trade-frontend-server-script
+    files:
+      - frontend-server.mjs
+
+generatorOptions:
+  disableNameSuffixHash: true
+
 commonLabels:
   env: prod