Ingest Runs (Multipart)

Ingests multiple runs, feedback objects, and binary attachments in a single multipart/form-data request. Part‑name pattern: <event>.<run_id>[.<field>] where event ∈ {post, patch, feedback, attachment}.

• post|patch.<run_id> – JSON run payload.
• post|patch.<run_id>.<field> – out‑of‑band run data (inputs, outputs, events, error, extra, serialized).
• feedback.<run_id> – JSON feedback payload (must include trace_id).
• attachment.<run_id>.<filename> – arbitrary binary attachment stored in S3. Headers: every part must set Content-Type and either a Content-Length header or length parameter. Per‑part Content-Encoding is not allowed; the top‑level request may be Content-Encoding: gzip or Content-Encoding: zstd. Best performance for high‑volume ingestion.