Add Minds to an Audience

Adds one Mind (mindId) or several Minds (mindIds) to an Audience. Requires a JSON object within 64 KiB and at most 1,000 supplied IDs before deduplication. Owner only; collaborators and viewers receive 404. Membership capacity and authorization are rechecked in a single transaction; concurrent additions cannot both consume the last available slot. Responses, including refusals, are private and non-cacheable. Unexpected storage or plan-resolution failures return a generic 500. Every Mind must be owned by the caller or public, otherwise nothing is added. Minds that are already members are ignored, so the call is idempotent; added reports the number of distinct IDs in the request, not the number of new memberships. Newly added Minds are sorted into the Audience's ready Formations in the background, and default Formations are seeded if the Audience had none. In the background each added Mind is also placed on the Audience's charts from the facts its own record holds (never invented; its own record is not changed), the Audience's allocation audit is measured again on the current members, and members whose training failed are retrained. Use mindIds rather than the retired mindId/mindIds fields.