Ruling budget-table-evict-oldest. FixedWindowBudget keeps two linked lists (window start, last use among keys
with permits left) so eviction and expiry are O(1); a spent key is never evicted, and a table full of spent keys
refuses a new key as TableFull with the true wait. Accounts get their own cast table. The vote page checks the
subject before spending any key, and the refusal names its reason: cast budget, mint budget, or a busy table.
Not verified by a build yet at this commit.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
436a02864f