Fix Cursor Placement in Checkbox Lists by pointing to the correct node (cross-browser improvement)

[Serranosoft]

This PR addresses a cursor placement issue in checkbox lists

• Previously, setCollapse() was called on the <ol> node. This works correctly in Chrome, Safari, and all mobile WebViews, but the online example does not behave correctly in Firefox desktop and the cursor is placed incorrectly after the checkbox.

• This change ensures that setCollapse() points to the <li> node containing the checkbox, which aligns with the correct HTML semantics and guarantees consistent behavior across all browsers, including Firefox desktop.

Notes

• No changes affect Chrome, Safari, or mobile WebViews; they continue to function as before.

• This fix is only required for the Firefox desktop online example due to its stricter handling of contenteditable and non-editable elements.

• Improves cross-browser consistency for checkbox lists in the online example.

• Does not affect other parts of the editor where setCollapse is used.

Changes

// Previously
foNode = node.firstChild; // <ol>

// Fixed
foNode = node.firstChild.firstChild; // <li> containing the checkbox
setCollapse(foNode);