[IAmJSD]

Part 1 of 7 in the bank stack: virtual cards and crypto wallets for nibblets.

What this adds

• @nibblet/bank: the BankPlugin contract every bank fulfils (issue, find, reveal, inspect, close, balance), a loader that turns plugins on from the server's environment, and the logic plugins share:
  • budget maths in minor units
  • wallet keys derived from a treasury secret and the card's id, so none is ever stored
  • BankError for messages that are safe to show
• Protocol:
  • cards, which move through pending → open → closing → closed
  • the card file a nibblet reads its details from
  • per-asset spendingLimits on each nibblet, which only the person sets; none means no cards
• Database: a cards table and nibblets.spending_limits (migration 0010_bank).

Stack

1. This PR: plugin base, protocol, database
2. card_request / card_list / card_kill tools, and the runner writing card files
3. Slash as the card bank
4. Bitcoin and Ethereum banks
5. UI
6. Setting banks up from Settings, with forms their plugins describe (Set banks up from Settings, with forms their plugins describe #31)
7. Several banks on one plugin: two Slash accounts, say (Let several banks share a plugin: two Slash accounts, say #32)

Screenshots

From #28's UI, in the mock server (?mock=1): the per-currency limits this adds, which only the person sets.

Review fixes

• An open card now counts against a limit in full whenever it was made, so cards left open from an earlier day or week can't pile up past a per-period limit. A closed card still counts what was spent on it in the period it was made in.

Checks

pnpm format:check, pnpm -r typecheck and pnpm test pass on this branch on its own.

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Generated by Claude Code