Drop the Netto row for Kleinunternehmer invoices

Netto = Gesamt is structural under §19 UStG (no tax component ever
existed), not the coincidental 0%-this-one-sale case vatExempt orders
are in — showing it right under the §19 notice just duplicated Gesamt.
At the user's own request after reviewing a real invoice.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/invoicePdf.tsx

@@ -425,19 +425,28 @@ export function InvoiceDocument({ order, seller }: { order: InvoiceOrder; seller
                   by hand. Shown on every invoice, not just B2B/non-exempt
                   ones — on a vatExempt order Netto and Gesamt happen to be
                   the same figure (0% tax), but the row stays for layout
-                  consistency across every invoice this shop issues. Placed
-                  last (after the MwSt annotation, not before it) — see
-                  that annotation's own comment above for why the order
-                  matters here. Styled with the same small/muted
-                  vatNoteLabel/vatNoteValue as that annotation, not the
-                  larger summaryLabel/summaryValue the build-up rows above
-                  Gesamt use — Netto is supplementary detail *below* the
-                  hero Gesamt figure, same visual tier as the tax
-                  breakdown, not another primary line competing with it. */}
-              <View style={styles.nettoRow}>
-                <Text style={styles.vatNoteLabel}>Netto</Text>
-                <Text style={styles.vatNoteValue}>{formatPrice(rateGroups.reduce((sum, g) => sum + g.net, 0))}</Text>
-              </View>
+                  consistency across every invoice this shop issues. The one
+                  exception is `kleinunternehmer` (built 2026-07-24, at the
+                  user's own request): there Netto = Gesamt for a
+                  structural reason, not a coincidental one (§19 UStG means
+                  there was never a tax component to subtract in the first
+                  place), and the row would just look like a second,
+                  redundant total sitting directly under the §19 notice
+                  above rather than genuinely new information. Placed last
+                  (after the MwSt annotation, not before it) — see that
+                  annotation's own comment above for why the order matters
+                  here. Styled with the same small/muted vatNoteLabel/
+                  vatNoteValue as that annotation, not the larger
+                  summaryLabel/summaryValue the build-up rows above Gesamt
+                  use — Netto is supplementary detail *below* the hero
+                  Gesamt figure, same visual tier as the tax breakdown, not
+                  another primary line competing with it. */}
+              {!order.kleinunternehmer && (
+                <View style={styles.nettoRow}>
+                  <Text style={styles.vatNoteLabel}>Netto</Text>
+                  <Text style={styles.vatNoteValue}>{formatPrice(rateGroups.reduce((sum, g) => sum + g.net, 0))}</Text>
+                </View>
+              )}
             </View>
             {paid && (
               <View style={styles.paidBadgeRow}>