Reduce LiteLLM log volume to errors only

Set LITELLM_LOG=ERROR and JSON_LOGS=True so uvicorn INFO
access lines (MCP and UI traffic) are suppressed per LiteLLM docs.

Co-authored-by: Nick Trochalakis <[email protected]>

butane/ai.yaml.tftpl

@@ -38,6 +38,8 @@ systemd:
           -e STORE_MODEL_IN_DB=True \
           -e LITELLM_MASTER_KEY=${litellm_master_key} \
           -e LITELLM_SALT_KEY=${litellm_salt_key} \
+          -e LITELLM_LOG=ERROR \
+          -e JSON_LOGS=True \
           -p 4000:4000 \
           docker.litellm.ai/berriai/litellm:main-stable
         ExecStop=/usr/bin/docker stop litellm