fix: crop save dropped blue channel brightness/contrast offset (v1.4.2)

m[13] (blue alpha coefficient, always 0) was read as the blue offset instead of
m[14], so saved JPEGs lost the blue brightness/contrast offset and came out with a
color cast. Saturation/rotate were unaffected (no offsets).

Also: version 1.4.2, CHANGELOG entry, dist/ ships imajviewer_1.4.2_amd64.deb
(replaces 1.4.1).

lib/services/crop_save_service.dart

@@ -143,7 +143,7 @@ class CropSaveService {
       final r = pixel.r.toDouble(), g = pixel.g.toDouble(), b = pixel.b.toDouble();
       pixel.r = (m[0] * r + m[1] * g + m[2] * b + m[4]).clamp(0, 255).round();
       pixel.g = (m[5] * r + m[6] * g + m[7] * b + m[9]).clamp(0, 255).round();
-      pixel.b = (m[10] * r + m[11] * g + m[12] * b + m[13]).clamp(0, 255).round();
+      pixel.b = (m[10] * r + m[11] * g + m[12] * b + m[14]).clamp(0, 255).round();
     }
   }
 }