Add an agent trace

Add an agent trace/transcript to the index.

Accepts traces as a string in Hyperdoc format (native), Vercel AI SDK format, or OpenClaw JSONL format. The format is auto-detected if not specified.

Hyperdoc format (JSON array, snake_case with type discriminators):

{"history": "[{\"type\": \"trace_message\", \"role\": \"user\", \"text\": \"Hello\"}]"}

Vercel AI SDK format (JSON array, camelCase):

{"history": "[{\"role\": \"user\", \"content\": \"Hello\"}]"}

OpenClaw JSONL format (newline-delimited JSON):

{"history": "{\"type\":\"session\",\"id\":\"abc\"}\n{\"type\":\"message\",\"message\":{\"role\":\"user\",...}}"}