phase3: nullfix.py batch script — bang/late/param-nullable

Automated null-safety fixes driven by dart analyze (no corruption):
- unchecked_use_of_nullable_value: insert '!' on receiver (property/method/[]/op)
- not_initialized field/var: mark 'late'
- missing_default_value_for_parameter: nullable param
Errors: 2374(peak) -> 907

lib/widgets/desktop/desktop_new_comment.dart

@@ -34,13 +34,13 @@ class DesktopNewComment extends StatefulWidget {
 }
 
 class DesktopNewCommentState extends State<DesktopNewComment> {
-  Comment comment;
+  late Comment comment;
 
-  bool _showProgress;
+  late bool _showProgress;
 
-  double _progress;
+  late double _progress;
 
-  double rating;
+  late double rating;
 
   bool isSubmitting = false;
 
@@ -203,7 +203,7 @@ class DesktopNewCommentState extends State<DesktopNewComment> {
       children: <Widget>[],
     );
 
-    if (comment != null && comment.images.length > 0) {
+    if (comment != null && comment.images!.length > 0) {
       for (ProductImage image in comment.images) {
         row.children.add(
           Container(
@@ -275,7 +275,7 @@ class DesktopNewCommentState extends State<DesktopNewComment> {
           child: Icon(
             Icons.add,
             size: 60.0,
-            color: comment == null || comment.images.length < 3 ? Colors.lightBlue : Colors.black12,
+            color: comment == null || comment.images!.length < 3 ? Colors.lightBlue : Colors.black12,
           ),
           decoration: BoxDecoration(
             color: Colors.white70,
@@ -300,7 +300,7 @@ class DesktopNewCommentState extends State<DesktopNewComment> {
           ),
         ),
         onTap: () {
-          if (comment == null || comment.images.length < 3) {
+          if (comment == null || comment.images!.length < 3) {
             showDialog(
                 context: mainContext,
                 barrierDismissible: true,