fix(bookkeeping): settle öre differences to 3740 and improve supplier-invoice matching (#699)

Whole-krona Bankgiro/Swish payments of öre-bearing invoices were stranded
as partially_paid forever (e.g. 11 231 paid on an 11 231,25 invoice left
0,25 kr open). Book the sub-krona residual to BAS 3740 (Öres- och
kronutjämning) and settle the invoice in full, on both the supplier- and
customer-invoice match flows.

New shared pure helpers buildSupplierPaymentClearingLines +
planSupplierPayment mirror the customer-side primitives; routing preview
and commit through the same builder also fixes two pre-existing
preview↔commit drifts (payment account + line descriptions). Öre
absorption is accrual-only — cash entries book the full invoice, so
absorbing there would hide a 1930 discrepancy.

Also improves supplier-invoice ↔ bank matching:
- Pass-3 date window now spans [invoice_date-5, due_date+5] instead of
  due_date ±5, so early payments auto-match; an ambiguity guard demotes
  non-unique amount matches to suggestions.
- New retroactive matcher (on supplier_invoice.registered/.approved)
  surfaces the settling bank payment when the invoice is registered after
  the payment was imported. Matches are written as suggestions for
  one-click confirm-to-book, never silently auto-booked.

Tests: new unit tests for both pure helpers; extended matching, handler,
customer öre, and route suites. Full suite green (407 files / 5364 tests).

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

components/transactions/InvoiceMatchDialog.tsx

@@ -449,7 +449,14 @@ export default function InvoiceMatchDialog({
               // built by buildInvoicePaymentClearingLines, which posts the
               // FX diff to 3960/7960 so the books balance correctly even
               // when the on-screen numbers can't be naively compared.
-              const amountsMatch = sameCurrency && Math.abs(txAbs - invRemaining) < 0.01
+              const diff = Math.abs(txAbs - invRemaining)
+              const amountsMatch = sameCurrency && diff < 0.01
+              // A sub-krona SEK difference is öresavrundning: the backend books
+              // it to 3740 and settles the invoice in full instead of leaving it
+              // delbetald (see ORE_ROUNDING_SETTLEMENT_MAX). SEK only — keep the
+              // 1 kr band in sync with the server constant.
+              const isOreRounding =
+                sameCurrency && transaction.currency === 'SEK' && diff >= 0.01 && diff < 1.0
 
               if (amountsMatch) {
                 return (
@@ -460,6 +467,19 @@ export default function InvoiceMatchDialog({
                 )
               }
 
+              if (isOreRounding) {
+                return (
+                  <div className="flex items-start gap-2 p-3 rounded-lg bg-success/10 text-success">
+                    <CheckCircle2 className="h-4 w-4 flex-shrink-0 mt-0.5" />
+                    <p className="text-sm font-medium">
+                      {t('ore_rounding_note', {
+                        amount: formatCurrency(diff, transaction.currency),
+                      })}
+                    </p>
+                  </div>
+                )
+              }
+
               return (
                 <div className="flex items-start gap-2 p-3 rounded-lg bg-warning/10 text-warning-foreground">
                   <AlertTriangle className="h-4 w-4 flex-shrink-0 mt-0.5" />