patches: squash perf fixes into respective patches, clean 9-patch series

Performance fixes folded back:
- BUF_CHARS_MODIFF → patch 0002 (implement buffer accessibility element)
- UAZoomEnabled cache + rate-limit → patch 0000 (Zoom integration)

Also in patch 0000: ns_zoom_face_is_selected (standalone compilation).
Also in patch 0001: ns_accessibility_enabled defaults to nil.

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

@@ -1,7 +1,7 @@
-From 2428a8f16873dab87284da544a7da4bbffff48a5 Mon Sep 17 00:00:00 2001
+From 014826c0b4de37f5e6adbd85032282dabae623a3 Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 12:58:11 +0100
-Subject: [PATCH 05/11] ns: add interactive span elements for Tab navigation
+Subject: [PATCH 5/9] ns: add interactive span elements for Tab navigation
 
 * src/nsterm.m (ns_ax_scan_interactive_spans): New function.
 (EmacsAccessibilityInteractiveSpan): Implement AXButton/AXLink
@@ -17,10 +17,10 @@ Tested on macOS 14.  Verified: Tab-cycling through org-mode links,
  1 file changed, 286 insertions(+)
 
 diff --git a/src/nsterm.m b/src/nsterm.m
-index 09f47ab..a056c1b 100644
+index b48f0c2..01751ce 100644
 --- a/src/nsterm.m
 +++ b/src/nsterm.m
-@@ -9224,6 +9224,292 @@ - (NSRect)accessibilityFrame
+@@ -9265,6 +9265,292 @@ - (NSRect)accessibilityFrame
  
  @end