UI fixes + Scan fix

packages/simplex_app/lib/views/contacts/add_contact_view.dart

@@ -176,15 +176,7 @@ class _AddContactViewState extends State<AddContactView> {
             result = scanData;
             await controller.pauseCamera();
             if (result != null) {
-              await Navigator.push(
-                context,
-                MaterialPageRoute(
-                  builder: (_) => QRCodeDetailsView(
-                    barcode: result!,
-                  ),
-                ),
-              );
-              await controller.resumeCamera();
+              Navigator.of(context).pop(true);
             }
           });
         });

packages/simplex_app/lib/views/scan_invitation/scan_invitation_view.dart

@@ -30,6 +30,7 @@ class ScanInvitationView extends StatelessWidget {
                 onTap: () => _showConnection(context),
                 child: Image.asset(
                   'assets/code.png',
+                  height: _size.height * 0.3
                 ),
               ),
               SizedBox(height: _size.height * 0.04),