patches: restructure per reviewer feedback

Major changes:
1. Zoom separated into standalone patch 0000
   - UAZoomChangeFocus in ns_draw_window_cursor
   - Fallback in ns_update_end for window-switch tracking
   - No overlayZoomActive (source of split/switch/move bug)

2. VoiceOver patches 0001-0008 are now Zoom-free
   - All UAZoom*, overlayZoom*, kUAZoomFocus references removed
   - lastAccessibilityCursorRect kept for VoiceOver bounds queries
   - Commit messages cleaned of Zoom references

3. README.txt and TESTING.txt rewritten for new structure

Addresses reviewer (Stéphane Marks) feedback:
- Keep Zoom patch separate from VoiceOver work
- Design discussion needed for non-Zoom patches
- Performance: ns-accessibility-enabled=nil for zero overhead

patches/0004-ns-add-interactive-span-elements-for-Tab-navigation.patch

@@ -1,4 +1,4 @@
-From 4ddd874dcf700fc830796ce16d949ba7d2fa4d78 Mon Sep 17 00:00:00 2001
+From 9da1c8d18d2e70fc53f1f8e061a963c3adf8d960 Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 12:58:11 +0100
 Subject: [PATCH 4/8] ns: add interactive span elements for Tab navigation