feat(bookkeeping): verifikationsserie per bankkonto for bank-transaction bookings (#2160)

* feat(bookkeeping): verifikationsserie per bankkonto for bank-transaction bookings

A company running several bank accounts (main bank on A, company card on M,
both imported via CSV) could not route each account's bookings into its own
series: every bank_transaction booking took the single company-wide default
from default_voucher_series_per_source_type.

- cash_accounts.voucher_series (nullable, single letter): per-account override,
  editable under Inställningar → Bokföring → Verifikationsserier per bankkonto
  (new PATCH /api/cash-accounts/[id]).
- resolveCashAccountVoucherSeries(): step 2 of the resolution order
  (explicit pick → account override → per-type map → A). Wired into the book
  route and createTransactionJournalEntry, which covers categorize, the agent,
  pending operations and the v1 API.
- Booking dialog gets the series picker, seeded from the server via
  /voucher-sequences/next?source_type&cash_account_id so dialog and route can
  never disagree. An unresolved embedded picker omits voucher_series so a
  stray 'A' never overrides the account's series.

Scope: bank_transaction bookings only. Invoice settlements matched from the
bank keep their payment series; bulk-book resolves inside its RPC (see
DECISIONS.md).

Migration applied to staging as 20260902121420.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JWSLbQc3jgpfqnxWe6nteh

* fix(bookkeeping): audit and document the per-bankkonto series, tighten preview and PATCH

Consolidated pass over the PR #2160 findings (skeptics, CodeRabbit, Swedish
compliance review):

- Behandlingshistorik (BFNAR 2013:2 p. 9.16): changing cash_accounts.voucher_series
  is a behandlingsregel that outranks the audited per-type map. New trigger
  audit_cash_accounts_voucher_series (UPDATE only, WHEN the series changes, so
  bank-sync churn never logs), cash_accounts added to AUDITED_TABLES and the
  audit_log filter, "Bankkonto ... Verifikationsserie: (tomt) -> M" events in
  the report, pg-real test. Applied to staging as 20260902124513.
- Systemdokumentation (p. 9.2-9.15): revision/systemdokumentation.json gains a
  verifikationsserier_regler block with the resolution order and the two
  exceptions (invoice settlements, samlingsverifikat); the per-account mapping
  itself is in data/cash_accounts.json.
- Settings picker uses the same closed list as the manual verifikat form
  (presets plus letters already in use) instead of all 26 letters; strings
  moved to messages/sv.json and messages/en.json.
- /voucher-sequences/next applies the account override only for
  source_type=bank_transaction (CodeRabbit), so a manual-entry preview cannot
  show a series the entry will not get.
- Book route resolves the series from the account the row ends up on after a
  stranded-row repoint, not the stale one.
- PATCH /api/cash-accounts/[id] answers 404 for a non-UUID id instead of a
  Postgres cast 500; the series lookup logs a warning when it fails open.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JWSLbQc3jgpfqnxWe6nteh

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

supabase/migrations/20260902121420_cash_accounts_voucher_series.sql

@@ -0,0 +1,19 @@
+-- Verifikationsserie per bankkonto.
+--
+-- A company that runs several bank accounts (main bank on series A, a
+-- company-card account on series M, both imported via CSV) wants entries
+-- booked from each account to land in that account's own series. Until now
+-- every bank-transaction booking took the single company-wide default from
+-- company_settings.default_voucher_series_per_source_type.bank_transaction.
+--
+-- NULL means "no override": the engine keeps resolving the series from the
+-- per-source-type map, so existing accounts and bookings are untouched.
+-- Single uppercase letter, same rule as journal_entries.voucher_series.
+ALTER TABLE public.cash_accounts
+  ADD COLUMN IF NOT EXISTS voucher_series text
+  CHECK (voucher_series IS NULL OR voucher_series ~ '^[A-Z]$');
+
+COMMENT ON COLUMN public.cash_accounts.voucher_series IS
+  'Optional verifikationsserie (single letter A-Z) for entries booked from this bank account. NULL = follow the per-source-type default in company_settings.';
+
+NOTIFY pgrst, 'reload schema';

supabase/migrations/20260902124513_cash_accounts_voucher_series_audit.sql

@@ -0,0 +1,18 @@
+-- Behandlingshistorik for the per-bankkonto verifikationsserie.
+--
+-- cash_accounts.voucher_series (20260902121420) takes precedence over the
+-- company-wide default_voucher_series_per_source_type map, which is already
+-- audited and reported as a behandlingsregel (BFNAR 2013:2 p. 9.16 second
+-- paragraph: changes that affect how bokföringsposter are processed, and when
+-- they were introduced). The override must leave the same dated trace.
+--
+-- UPDATE only, and only when the series itself changes: cash_accounts rows are
+-- created and touched by bank sync (balances, names, enabled flags) many times
+-- a day, and none of that is a behandlingsregel. Same WHEN pattern as the
+-- categorization_templates learning filter in 20260901103000.
+DROP TRIGGER IF EXISTS audit_cash_accounts_voucher_series ON public.cash_accounts;
+CREATE TRIGGER audit_cash_accounts_voucher_series
+  AFTER UPDATE ON public.cash_accounts
+  FOR EACH ROW
+  WHEN (OLD.voucher_series IS DISTINCT FROM NEW.voucher_series)
+  EXECUTE FUNCTION public.write_audit_log();