feat(bank): multi-bank chequera — required bankAccountId, per-account scoping

The office keeps more than one operating account (Utilities banks in MXN,
Seguros in USD), but bank_transactions was a single implicit MXN register by
design. Adds Bank/BankAccount and makes every read and write in the module
scoped to exactly one account.

Schema:
- Bank / BankAccount. Currency is fixed per account and BankTransaction has
  no currency column of its own — a movement inherits its account's, the way
  a real bank account doesn't mix currencies.
- BankTransaction.bankAccountId, required. A movement with no known account
  isn't reconcilable against a statement.
- @@index([bankAccountId, transactionDate]): every read now filters by
  account and orders/groups by date.

Migration:
- backfill_bank_accounts.py seeds Scotiabank + "Utilities — Scotiabank (MXN)"
  and backfills all 22,669 existing rows onto it, then promotes the column to
  NOT NULL and attaches the FK. Standalone because prisma db push cannot add
  a required column to a populated table. Idempotent; re-running once a second
  account exists does not re-point rows.
- run_all.py runs it (both modes) before transform_bank.py, which now resolves
  the account by label and fails fast if it is missing.

API:
- ?bankAccountId= required on list/stats/facets/summary — not optional with an
  "all accounts" default, since summing an MXN and a USD register repeats the
  currency-collapsing mistake the billing module exists to prevent. Missing is
  400, unknown is 404.
- facets() had no account clause at all and summary() has two raw-SQL rollups;
  all three are now parameterised. Scoping only one of summary's queries would
  leave the year list and its drill-down describing different books.
- New bank/accounts + bank/banks sub-resource under a MANAGER
  bank:manage-accounts ability. currency is absent from the update DTO: booked
  movements are denominated in it, so editing would re-denominate history.
  Capture into a closed account is rejected.

Web:
- /banco gains an account picker (remembered per browser) and reads every
  figure in the selected account's currency; the "single currency (MXN)"
  doc-comment and the hardcoded MXN formatting are gone.
- New /banco/cuentas for banks and accounts. Accounts are closed, never
  deleted — the FK is required, so deleting one would destroy its register.
- /inicio's chequera card names the account it is reading instead of implying
  a single register.

Verified against dev + browser: a second USD account showed full read/write
isolation from the MXN register, whose totals were unchanged (22,669
movements, net 1,014,266.97).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

RESUME.md

@@ -381,9 +381,18 @@ for what's actually next.
      insurance/servicios/fideicomiso split the migration comment implied. A
      classifier would invent data, so `categoryId` stays null and the module does
      not filter on it. Register is browsable by date/payee/amount/cheque instead.
-     (c) **Single currency (MXN).** `bank_transactions` has no currency column and
-     every `amountInWords` is spelled out in PESOS — so, unlike the customer
-     ledger, everything here is one currency and not split per-currency.
+     (c) ~~**Single currency (MXN).**~~ **SUPERSEDED 2026-07-27 by the multi-bank
+     chequera** (step 11, `docs/RECEIPT_CAPTURE_SPEC.md` §3). The office keeps
+     more than one register, so `bank_transactions` now carries a **required**
+     `bankAccountId` and every read in the module is scoped to exactly one
+     `BankAccount`, whose `currency` the movements inherit — there is still no
+     currency column on the movement itself, because a real bank account doesn't
+     mix currencies. All 22,669 migrated rows are the Utilities/Scotiabank MXN
+     account (backfilled by `migration/backfill_bank_accounts.py`, which
+     `run_all.py` runs before `transform_bank.py`), which is why every
+     `amountInWords` is still spelled out in PESOS. There is deliberately no
+     "all accounts" option: summing an MXN and a USD register would repeat the
+     currency-collapsing mistake the billing module warns against.
      (d) **The "acumulado" is net movement since the register opened, not a bank
      balance** — SCOTHIA carries no opening balance (its `ban` table holds only the
      bank's name), so the running total starts at 0 in 2013. Labelled as such in
@@ -391,9 +400,18 @@ for what's actually next.
      (e) Sign convention (from `transform_bank.py`): positive = ingreso,
      negative = egreso, exactly zero = a cancelled/void cheque (787 of 791 say
      CANCELADO/VOID) — voids are excluded from both the income and expense sides.
+     (f) **Multi-account since 2026-07-27.** `/banco` opens on an account picker
+     (the last account is remembered per browser) and reads every figure in that
+     account's currency; `/banco/cuentas` manages banks and accounts under a new
+     MANAGER `bank:manage-accounts` ability. Accounts are never deleted — the
+     `bankAccountId` FK is required, so a used account can only be *closed*
+     (`active: false`), which hides it from new captures but keeps its history
+     readable. An account's currency is immutable after creation, since its
+     booked movements are denominated in it.
    - Full pipeline reproducible in one command: `run_all.py --env <env>` runs customers →
-     properties → policies → transactions → prune → bank → blobs in order (all idempotent);
-     add `--stage` to re-extract from the Access files first. Verified end-to-end against dev.
+     properties → policies → transactions → prune → bank accounts → bank → blobs in order
+     (all idempotent); add `--stage` to re-extract from the Access files first. Verified
+     end-to-end against dev.
 
 5. **Infra** — **DONE.** Dev MySQL deployed to the cubex Swarm via the Portainer API as stack
    `jorgecuadros-dev-db` (MySQL 8.4, `192.168.4.212:3307`, node `cubex` labeled