chore: add simulator docker-compose overlay

Integrates home-device-simulator as optional Docker services.

Usage:
  docker compose -f docker-compose.yml -f docker-compose.simulator.yml up

Services added:
  - simulator  : backend Go TR-069 sur port 9898, partage mongodb et réseau ACS
  - simulator-ui: UI nginx sur port 3000, env injecté via config/simulator-ui-env.js

Flux:
  simulator → ACS via http://app:8080/cwmp10 (réseau Docker interne)
  ACS → simulator Connection Request via http://simulator:9898/...

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

config/simulator-ui-env.js

@@ -0,0 +1,11 @@
+// Injecté au runtime par docker-compose (volume mount).
+// Permet au navigateur de savoir où appeler le backend du simulateur.
+window.__ENV__ = {
+  VITE_BACKEND_API_URL: "http://localhost:9898",
+  VITE_HOST: "Local Dev",
+  VITE_RELEASE_NAME: "dev",
+  VITE_SAMPLE_DATA: "sampledevice.json",
+  VITE_ACS_CHECK_ENABLED: "false",
+  VITE_KARMA_GUI_SSO_LOGIN_URL: "",
+  VITE_KARMA_GUI_URL: ""
+};