- Add PromptGenerationTraceInfo trace entity with operation_type field
- Implement telemetry for rule-generate, code-generate, structured-output, instruction-modify operations
- Emit metrics: tokens (total/input/output), duration histogram, requests counter, errors counter
- Emit structured logs with model info and operation context
- Content redaction controlled by ENTERPRISE_INCLUDE_CONTENT env var
- Fix user_id propagation in TraceTask kwargs
- Fix latency calculation when llm_result is None
No spans exported - metrics and logs only for lightweight observability.