[Feature]: Integrate BAML for structured output in watchdog

[HyunggyuJang]

Problem Statement

Currently, open router is used and output parsing is relied solely on prompting, which is fragile.

Proposed Solution

Use BAML by wrapping openrouter endpoint: https://docs.boundaryml.com/ref/llm-client-providers/openai-generic

It would be better to allow to replace the LLM endpoint so that the user can use local LLMs like ollama.

FYI, from claude agent sdk side, you can use structured output feature for the same purpose: https://platform.claude.com/docs/en/agent-sdk/structured-outputs

Alternatives Considered

No response

Feature Area

Policy engine / evaluation

Related Harness

None

Use Case

No response

Additional Context

No response

[backnotprop]

@HyunggyuJang will do as well as implement formal structured output via api. Initial implementation was rushed.