Get Llm Proxy Request Bodies

The raw Vapi payload, the translated Anthropic body, and the response.

Its own endpoint deliberately: these are caller PII and easily hundreds of KB, so they must never ride along in a list payload. bodies_imported_at set with a null vapi_body means the body was dropped (over the proxy's 256 KB cap) or purged by tasks.purge_llm_proxy_bodies, not that it never existed.