fix(import): label the SIE preview IB total as "summa debet", not "IB Summa" (#2142)

The fourth stat card in the SIE preview showed the debit-side total of the
opening-balance voucher under the label "IB Summa". A user read it as the
net ingående balans and could not reconcile it against any single figure.

- Relabel the card "IB, summa debet" and add a one-line helper saying it is
  the sum of all debit balances in IB, not a single account balance. The
  number equals "Total debet" in the Balansräkning (IB) card right below.
- Review step: "Skapar IB-verifikation, summa debet X" instead of
  "Skapar verifikation för IB på X".
- Comment the field in generateImportPreview so the meaning is explicit.

No data or logic change: openingBalanceTotal keeps its semantics.


Claude-Session: https://claude.ai/code/session_01AvaV9n4GswzF2Mq932PXTJ

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

components/import/ImportReviewStep.tsx

@@ -350,7 +350,7 @@ export default function ImportReviewStep({
               </Label>
               <p className="text-sm text-muted-foreground">
                 {hasOpeningBalances
-                  ? `Skapar verifikation för IB på ${formatCurrency(preview.openingBalanceTotal)}`
+                  ? `Skapar IB-verifikation, summa debet ${formatCurrency(preview.openingBalanceTotal)}`
                   : 'Inga ingående balanser i filen'}
               </p>
               {existingIbCount > 0 && (