refactor(ui5-li): use hasConfigurableMode guard and fix _editMode JSDoc

- Replace "\_editMode" in listItem type guard with the existing
  hasConfigurableMode pattern for consistency with the rest of List.ts
- Clarify JSDoc: F2 is handled by ListItem, F7 by the parent List

Author: kgogov

packages/main/src/List.ts

@@ -1416,7 +1416,7 @@ class List extends UI5Element {
 	onForwardBefore(e: CustomEvent) {
 		const listItem = e.target as ListItemBase;
 
-		if ("_editMode" in listItem && (listItem as ListItem)._editMode) {
+		if (listItem.hasConfigurableMode && (listItem as ListItem)._editMode) {
 			const allItems = this.getItems().filter(node => {
 				return "hasConfigurableMode" in node && node.hasConfigurableMode
 					&& (node as ListItem)._hasFocusableElements();
@@ -1447,7 +1447,7 @@ class List extends UI5Element {
 	onForwardAfter(e: CustomEvent) {
 		const listItem = e.target as ListItemBase;
 
-		if ("_editMode" in listItem && (listItem as ListItem)._editMode) {
+		if (listItem.hasConfigurableMode && (listItem as ListItem)._editMode) {
 			const allItems = this.getItems().filter(node => {
 				return "hasConfigurableMode" in node && node.hasConfigurableMode
 					&& (node as ListItem)._hasFocusableElements();

packages/main/src/ListItem.ts

@@ -197,7 +197,7 @@ abstract class ListItem extends ListItemBase {
 	 * Indicates whether the list item is in edit mode.
 	 * When active, Tab cycles through internal focusable elements
 	 * instead of navigating to the next list item.
-	 * Toggled by F2 or F7.
+	 * Toggled by F2; also set by the parent List on F7.
 	 * @private
 	 */
 	_editMode = false;