macOS Zoom is event-driven -- it only queries AXBoundsForRange after
receiving NSAccessibilitySelectedTextChangedNotification. Previous
version implemented the bounds methods but never posted notifications,
so Zoom never triggered a cursor position query.
Added:
- NSAccessibilityPostNotification(SelectedTextChanged) in ns_draw_window_cursor
- NSAccessibilityPostNotification(FocusedUIElementChanged) in windowDidBecomeKey
- accessibilityAttributeNames + accessibilityAttributeValue: for
NSAccessibilitySelectedTextRangeAttribute -> returns {0,0}
Old parameterized attribute API alone insufficient — macOS Zoom prefers
the new NSAccessibilityProtocol method accessibilityBoundsForRange:.
Also adds isAccessibilityElement returning YES.
Both APIs now implemented for compatibility across macOS versions.
