Format selected note lines together

Formatting a group of note lines now applies to the complete selection on web, the installed PWA, and the iPhone app.

• Select parent rows, nested rows, or a mixture of bullets, numbers, and checkboxes, then choose the list format once.
• Every selected line keeps its existing indentation, wording, and inline emphasis.
• Already-completed checkboxes remain completed when the selection stays a checklist.
• The entire conversion is one save and one Undo action.

Rows outside the selection and the hierarchy around them remain unchanged.