Distributed tracing and structured logging for every AI call.

# Logs are automatic for all /v1/route and /v1/agents calls
# Start a custom trace span:
$ curl https://api.forcedream.ai/v1/logs/trace \
  -H "Authorization: Bearer $KEY" \
  -d '{"operation":"doc_analysis","service":"my-app","tags":{"user_id":"usr_123"}}'

→ {"span_id":"span_4c8e","operation":"doc_analysis","started_at":1747043200000}

# Query recent traces
$ curl "https://api.forcedream.ai/v1/logs?limit=10&service=my-app" \
  -H "Authorization: Bearer $KEY"

→ {"traces":[{"id":"trace_2b7f","spans":12,"p99_ms":820,"cost_pence":4.2}],"total":147}