Asset panel grouped by kind with icons: assets are listed under a header per kind (Sprites, Behaviors, ...) with the count on the right, empty groups are not shown, every group starts folded when a project is opened, a click on the header folds and unfolds it, selecting an asset elsewhere unfolds its group and folding the group of the selected asset clears the selection; every asset kind has an SVG icon in src/editor/panels/icons/ drawn before the name, the pure rule for grouping and sorting lives in assetGroups.ts; the same icons replace the kind word in document tabs and the overflow menu (a list icon for the List tab, which also fixes the close x lying over the end of the active tab's text), stand before every entry of the + menu (Button got an icon option) and on the right of scene object rows instead of the type name; the colour swatch next to sprite names is gone from both panels; the SVG loader moved to src/ui/svg.ts for both icon sets; test hook assetRow unfolds the group and scrolls to the row, assetRowShown only reads, new hook menuIcons; e2e 4g and 4h, 14 and 44a check the icons (#176)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/ui/widgets/Menu.ts

@@ -15,6 +15,8 @@ export interface MenuItem {
   onSelect: () => void;
   danger?: boolean;
   disabled?: boolean;
+  /** SVG file in front of the label (see `ButtonOptions.icon`). */
+  icon?: string;
 }
 
 /** A hairline between two groups of entries; it is not selectable and matches no search. */
@@ -66,6 +68,7 @@ export class Menu extends Popup {
       const button = new Button(item.label, {
         variant: item.danger ? 'danger' : 'ghost',
         align: 'left',
+        icon: item.icon,
       });
       button.setEnabled(!item.disabled);
       button.onClick = this.closeThen(item.onSelect);
@@ -95,6 +98,13 @@ export class Menu extends Popup {
       .map((child) => (child instanceof Button ? child.text : null));
   }
 
+  /** Per entry of `rowsDrawn`, whether it shows an icon; `null` for a separator (test hook). */
+  iconsDrawn(): (boolean | null)[] {
+    return this.list.children
+      .filter((child) => child !== this.empty && child.visible)
+      .map((child) => (child instanceof Button ? child.hasIcon : null));
+  }
+
   private filter(): void {
     const query = this.search?.value.trim().toLowerCase() ?? '';
     const shown = query ? this.ranked(query) : groupsOf(this.rows);