Full-buffer syntax restyle makes NSTextView scroll jump on each keystroke

If an NSTextView syntax highlighter re-applies attributes across the entire NSTextStorage after every edit, the layout is invalidated. When storage.endEditing runs with allowsNonContiguousLayout on, NSLayoutManager re-estimates the heights of lines not yet laid out and, inside _resizeTextViewForTextContainer, calls scrollRangeToVisible on the old visible range. The clip view moves by hundreds of points, often to near the top of short files, then partly or fully settles back: the user sees the editor jump. Fix: apply attributes only to runs that actually changed, for example with a diff of the attribute runs or by restyling only the edited paragraph range. When you must replace text or toggle wrap, restore scroll by anchoring the first visible character plus a pixel offset rather than the numeric clip origin.