feat: enable Redis caching for LiteLLM

Configure LiteLLM to use existing Redis from core stack for caching:
- Enabled cache with Redis backend
- Set TTL to 1 hour for cached responses
- Uses core_redis container on default port

This will improve performance by caching API responses.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

ai/litellm-config.yaml

@@ -30,8 +30,13 @@ model_list:
 litellm_settings:
   drop_params: true
   set_verbose: false  # Disable verbose logging for better performance
-  # Disable LiteLLM caching (prompt caching at API level is separate)
+  # Enable caching with Redis for better performance
-  cache: false
+  cache: true
+  cache_params:
+    type: redis
+    host: redis
+    port: 6379
+    ttl: 3600  # Cache for 1 hour
   # Force strip specific parameters globally
   allowed_fails: 0
   # Modify params before sending to provider