POST /public/v1/workspace-grants

Grant a user's API key visibility into a workspace without a workspace membership. The granted user gains MEMBER-level access on grant-aware Public API endpoints (workspace listing and endpoints resolving scope through the shared workspace-scope helpers); remaining endpoints are being rolled onto the grant-aware path. Requires an OWNER or ADMIN membership on the target workspace (or a workspace key for it) — a key can never grant itself access.