Upload an attachment for offer generation

<Warning> **Coming soon.** This endpoint will be available by early July 2026. </Warning>

<small>Requires the ai-sdr:write scope (or a broader one that includes it).</small>

Uploads a single attachment whose id can be passed in attachmentIds of POST /v3/ai-sdr/offers/generate to seed the generation. Maximum size 10 MB; supported formats are .txt, .pdf, .doc, .docx, and .rtf.

Requires the AI SDR feature on the caller's team.