local dev setup + OPENAI_BASE_URL support + dashboard fix

- CLAUDE.md con arquitectura y comandos del proyecto
- env.example: agregar LIMIT_CONVERSATIONS, MAX_CHARS_PER_MESSAGE, OPENAI_BASE_URL
- docker-compose.override: puerto 3001, extra_hosts para modelo local en Linux
- OpenAI clients: soporte OPENAI_BASE_URL para apuntar a modelo local compatible
- stats.js: sync de órdenes en background, dashboard no bloquea al cargar
- package-lock: dbmate movido a prod dependencies

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.override.yaml

@@ -4,7 +4,7 @@
 services:
   app:
     ports:
-      - "3000:3000"
+      - "3001:3000"
     env_file:
       - .env
     environment:
@@ -13,3 +13,5 @@ services:
     volumes:
       - .:/usr/src/app
       - /usr/src/app/node_modules
+    extra_hosts:
+      - "host.docker.internal:host-gateway"