fix(invoices): show sub-cent Rundung in the editor totals preview

The live totals panel in the quote/invoice editor (LineItemsTable) summed the
per-line rounded totals and showed that as Total — so with crm_invoice_round_total
on, a 4 × (2.5h @ 32.25) invoice previewed CHF 322.52 while the saved invoice +
PDF correctly show 322.50 with a Rundung row. The preview now mirrors the backend.

- LineItemsTable gains a `roundTotal` prop. When set, it computes the clean net
  (full-precision sum rounded once — same rule as backend
  utils/invoiceRounding.cleanNetMinor, including the migration-119 priced
  sub-item override), shows a "Rundung" row for the drift, and folds it into the
  VAT base + Total. Off ⇒ unchanged (no row).
- Bill + Quote editors pass roundTotal from appSettings.crm_invoice_round_total.
- i18n: crm.lineItems.rounding (de "Rundung", en "Rounding").

The saved-invoice detail view already shows the stored clean total, so no change
there.

frontend/src/pages/admin/bills/BillEditorPage.tsx

@@ -675,7 +675,8 @@ export const BillEditorPage: React.FC = () => {
       <Card>
         <h3 className="font-semibold mb-2">{t('bills.section.lineItems', 'Line items')}</h3>
         <LineItemsTable items={lineItems} currency={currency} showDiscount={false}
-          vatRate={vatRate / 100} shippingAmount={shipping} onChange={setLineItems} />
+          vatRate={vatRate / 100} shippingAmount={shipping}
+          roundTotal={appSettings?.crm_invoice_round_total === true} onChange={setLineItems} />
         <div className="grid grid-cols-1 md:grid-cols-3 gap-3 mt-4">
           <VatRateSelect
             label={t('bills.field.vatRate', 'VAT rate %') as string}

frontend/src/pages/admin/quotes/QuoteEditorPage.tsx

@@ -621,6 +621,7 @@ export const QuoteEditorPage: React.FC = () => {
           showDiscount={true}
           vatRate={form.vatRate / 100}
           shippingAmount={form.shippingAmount}
+          roundTotal={appSettings?.crm_invoice_round_total === true}
           presets={liPresets?.presets || []}
           onChange={(items) => setForm((f) => ({ ...f, lineItems: items }))}
         />