fix(studio): store grid uses _ModuleIcon (aligned icons + icon URLs)

The grid cell rendered a bare category glyph in a CircleAvatar; the detail
view uses _ModuleIcon (module icon URL with category fallback). Grid now
uses _ModuleIcon too — consistent, aligned, shows per-module icons.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/pages/store.dart

@@ -1899,16 +1899,10 @@ class _StoreCardState extends State<_StoreCard> {
                   children: [
                     Row(
                       children: [
-                        CircleAvatar(
+                        _ModuleIcon(
+                          iconUrl: item.iconUrl,
+                          category: item.category,
                           radius: 18,
-                          backgroundColor: theme.colorScheme.primary.withValues(
-                            alpha: 0.12,
-                          ),
-                          child: Icon(
-                            _iconForCategory(item.category),
-                            size: 18,
-                            color: theme.colorScheme.primary,
-                          ),
                         ),
                         const SizedBox(width: ChainSpace.sm),
                         Expanded(