User-facing society removal from the Digital Twins tab.

Branches on the society's source_mode:

• Mode 2 (customer/mixed) societies are fully deleted (personas, Gold, Bronze/Silver, GCS) — same cascade as the admin panel — but ONLY when the society belongs to no organization other than the caller's, so a shared artifact is never destroyed out from under someone else.
• Mode 1 (market) societies — and any case where the mode is ambiguous or the society is shared — are only unassigned from the caller's organization. The artifact is preserved and an admin can re-assign it later to restore access.

society_id is the UUID primary key minted by ensure_society_row (what the persona-groups gallery renders), not the "market/name" key.

Refused for an organization on limited access: it sees its customers (the society its Compass calls make) read-only.