Fiscal period and multi bank (#228)

* feat: add fiscal period backward chaining and entry date validation

Support creating fiscal periods before the earliest existing period
(backward chaining) for backfill scenarios, alongside the existing
forward chaining. The engine now validates that entry dates fall within
the selected fiscal period, with a Swedish error message. The journal
entry form auto-selects the matching period and shows a warning with
a CreatePeriodDialog when no period covers the entry date.


* feat: support multi-bank-account for imports and reconciliation

Plumb a configurable settlement account through the entire bank import
pipeline — mapping engine, transaction entries, ingest, and
reconciliation — so secondary bank accounts (e.g. 1931, 1932) work
correctly instead of hardcoding 1930. Adds a get_unlinked_bank_lines
RPC that generalizes the existing get_unlinked_1930_lines with a
fallback for backwards compatibility. The bank file import UI now shows
a bank account selector when multiple 19xx accounts exist. Also adds
default_vat_code/sru_code to account creation and fixes uploadDocument
argument order in enable-banking sync.

types/index.ts

@@ -2192,6 +2192,9 @@ export interface IngestOptions {
    * Used when SIE-imported entries overlap the sync date range
    * to prevent double-booking. */
   skipAutoCategorization?: boolean
+  /** Override the default settlement account (1930) for bank transactions.
+   * Used when importing to a secondary bank account (e.g., 1931). */
+  settlementAccount?: string
 }
 
 /** Result of the transaction ingestion pipeline */