update key and setup gpt-4o-mini as default llm

demos/use_cases/preference_based_routing/arch_config.yaml

@@ -13,10 +13,15 @@ listeners:
 llm_providers:
 
   - name: arch-router
-    access_key: $ARCH_API_KEY
+    access_key: $OPENAI_API_KEY
     provider_interface: arch
     model: Arch-Router
 
+  - name: gpt-4o-mini
+    provider_interface: openai
+    access_key: $OPENAI_API_KEY
+    model: gpt-4o-mini
+
   - name: gpt-4o
     provider_interface: openai
     access_key: $OPENAI_API_KEY

demos/use_cases/preference_based_routing/docker-compose.yaml

@@ -6,7 +6,7 @@ services:
     ports:
       - "8080:8080"
     environment:
-      - DEFAULT_MODELS=gpt-4o
+      - DEFAULT_MODELS=gpt-4o-mini
       - ENABLE_OPENAI_API=true
       - OPENAI_API_BASE_URL=http://host.docker.internal:12000/v1