Add a 12400x9600 canvas size

Fixes #1197

Signed-off-by: falkTX <falktx@falktx.com>

resources/ui/carla_settings.ui

@@ -689,6 +689,11 @@
                 <string>6200x4800</string>
                </property>
               </item>
+              <item>
+               <property name="text">
+                <string>12400x9600</string>
+               </property>
+              </item>
              </widget>
             </item>
             <item row="1" column="4">