Allow ChestShop shops owned by government accounts via G: signs

Let staff create ChestShops whose owner is a Treasury GOVERNMENT account.

• Owner line G:<display name> (case-insensitive), or G:#<base36 account id> for accounts whose name doesn't fit (sign lines are 15 chars; e.g. DCGovernmentJUD).
• Creation and owner access need ChestShop.government.<display name lowercased>; ChestShop.government.* grants all. ChestShop admins bypass.
• Archived accounts don't resolve.
• Money routes by account id (same synthetic-UUID path as firm shops); market registry classifies the owner as GOVERNMENT.

Note: almost all prod department accounts have unlimited overdraft, so a G: sell shop pays out without a funds check. The permission grant is the control.