fix: implement strict print grid and optical centering for business card

lib/pdf-business-card.tsx

@@ -100,7 +100,8 @@ const styles = StyleSheet.create({
   },
   frontContainer: {
     flex: 1,
-    paddingBottom: '18mm', // Push the logo up to center it in the area above the bar
+    paddingTop: '3mm', // Compensate for top bleed for perfect optical centering
+    paddingBottom: '18mm', // Leave space for the green bar
     justifyContent: 'center',
     alignItems: 'center',
   },
@@ -162,10 +163,10 @@ const styles = StyleSheet.create({
   // -- WHITE PAGE (Vorderseite) --
   backContainer: {
     flex: 1,
-    paddingTop: '8mm',
-    paddingBottom: '10mm',
-    paddingLeft: '6mm',
-    paddingRight: '6mm',
+    paddingTop: '7mm', // 3mm bleed + 4mm safe margin
+    paddingBottom: '14mm', // Prevent overlap with address footer
+    paddingLeft: '7mm',
+    paddingRight: '7mm',
     flexDirection: 'column',
   },
   backHeader: {
@@ -181,8 +182,8 @@ const styles = StyleSheet.create({
     flex: 1,
     height: 1.5,
     backgroundColor: '#011dff', // Brand blue line
-    marginLeft: 15,
-    marginRight: 10,
+    marginLeft: 12,
+    marginRight: 12,
   },
   accentDot: {
     width: 4,
@@ -276,7 +277,7 @@ const styles = StyleSheet.create({
     justifyContent: 'center',
     alignItems: 'center',
     position: 'absolute',
-    bottom: '3.5mm',
+    bottom: '7mm', // 3mm bleed + 4mm safe margin
   },
   addressFooterText: {
     fontSize: 7, // increased from 6