patches: fix O(position) lag — O(1) fast path in charposForAccessibilityIndex:

charposForAccessibilityIndex: walked composed character sequences
from the start of a visible run to the target AX index.  For a run
covering an entire ASCII buffer, this is O(cursor_position): moving
to line 10,000 requires ~500,000 iterations per call.

The method is called on every SelectedTextChanged notification
response (accessibilityBoundsForRange: from the AX server for cursor
tracking), making cursor movement O(position) in large files.

Fix: when ax_length == length for a run (all characters are single
AX index units — true for all ASCII/Latin text), the charpos offset
is simply ax_idx - run.ax_start.  O(1) instead of O(position).

Multi-byte runs (emoji, CJK, non-BMP) fall back to the sequence walk,
bounded by run length (visible window size), not total buffer size.

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

@@ -1,7 +1,7 @@
-From 7303dd3913729a454b44fe71219acbd612d624b4 Mon Sep 17 00:00:00 2001
+From a1c42c0fefc4cc942884c0fe44520717742e4dba Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 12:58:11 +0100
-Subject: [PATCH 5/9] ns: add interactive span elements for Tab navigation
+Subject: [PATCH 4/8] 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 7e3d57a..1a21f2e 100644
+index a73b7f5..98ff027 100644
 --- a/src/nsterm.m
 +++ b/src/nsterm.m
-@@ -9263,6 +9263,292 @@ - (NSRect)accessibilityFrame
+@@ -9271,6 +9271,292 @@ - (NSRect)accessibilityFrame
  
  @end