Stream traces as CSV or JSONL (sync export)

Cursor-streamed synchronous export of traces matching the same filters as GET /v1/traces. Rows are written directly to the response body — never buffered — and capped per plan (Starter: 100, Pro/Team/Business: 5000, Enterprise: unlimited). Hitting the cap sets X-TruLayer-Truncated: true; the payload is complete up to that row.

CSV columns (in order): id, project_id, model, environment, status, duration_ms, token_count, cost_usd, created_at.

JSONL emits one JSON object per line with the same keys.