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/0008-ns-announce-child-frame-completion-candidates-for-Vo.patch

@@ -1,7 +1,7 @@
-From 85259296769fe8e30d3fa2d8a7626729023c8691 Mon Sep 17 00:00:00 2001
+From 35a32f4802822ee77350a6d652aa45cca38e304c Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 16:01:29 +0100
-Subject: [PATCH 9/9] ns: announce child frame completion candidates for
+Subject: [PATCH 8/8] ns: announce child frame completion candidates for
  VoiceOver
 
 Completion frameworks such as Corfu, Company-box, and similar
@@ -109,7 +109,7 @@ index 2102fb9..dd98d56 100644
  @end
  
 diff --git a/src/nsterm.m b/src/nsterm.m
-index 3e005e0..d61a634 100644
+index c74eaf1..d2f88a5 100644
 --- a/src/nsterm.m
 +++ b/src/nsterm.m
 @@ -7398,6 +7398,112 @@ visual line index for Zoom (skip whitespace-only lines
@@ -268,7 +268,7 @@ index 3e005e0..d61a634 100644
        cachedTextStart = start;
  
        if (visibleRuns)
-@@ -9135,6 +9250,7 @@ - (void)postCompletionAnnouncementForBuffer:(struct buffer *)b
+@@ -9143,6 +9258,7 @@ - (void)postCompletionAnnouncementForBuffer:(struct buffer *)b
    ptrdiff_t currentOverlayStart = 0;
    ptrdiff_t currentOverlayEnd = 0;
  
@@ -276,7 +276,7 @@ index 3e005e0..d61a634 100644
    specpdl_ref count2 = SPECPDL_INDEX ();
    record_unwind_current_buffer ();
    if (b != current_buffer)
-@@ -9293,6 +9409,7 @@ - (void)postCompletionAnnouncementForBuffer:(struct buffer *)b
+@@ -9301,6 +9417,7 @@ - (void)postCompletionAnnouncementForBuffer:(struct buffer *)b
        self.cachedCompletionOverlayEnd = 0;
        self.cachedCompletionPoint = 0;
      }
@@ -284,7 +284,7 @@ index 3e005e0..d61a634 100644
  }
  
  /* ---- Notification dispatch (main entry point) ---- */
-@@ -9889,6 +10006,10 @@ - (void)dealloc
+@@ -9897,6 +10014,10 @@ - (void)dealloc
  #endif
  
    [accessibilityElements release];
@@ -295,7 +295,7 @@ index 3e005e0..d61a634 100644
    [[self menu] release];
    [super dealloc];
  }
-@@ -11338,6 +11459,9 @@ - (instancetype) initFrameFromEmacs: (struct frame *)f
+@@ -11346,6 +11467,9 @@ - (instancetype) initFrameFromEmacs: (struct frame *)f
  
    windowClosing = NO;
    processingCompose = NO;
@@ -305,7 +305,7 @@ index 3e005e0..d61a634 100644
    scrollbarsNeedingUpdate = 0;
    fs_state = FULLSCREEN_NONE;
    fs_before_fs = next_maximized = -1;
-@@ -12646,6 +12770,80 @@ - (id)accessibilityFocusedUIElement
+@@ -12654,6 +12778,80 @@ - (id)accessibilityFocusedUIElement
     The existing elements carry cached state (modiff, point) from the
     previous redisplay cycle.  Rebuilding first would create fresh
     elements with current values, making change detection impossible.  */
@@ -386,7 +386,7 @@ index 3e005e0..d61a634 100644
  - (void)postAccessibilityUpdates
  {
    NSTRACE ("[EmacsView postAccessibilityUpdates]");
-@@ -12656,11 +12854,59 @@ - (void)postAccessibilityUpdates
+@@ -12664,11 +12862,59 @@ - (void)postAccessibilityUpdates
  
    /* Re-entrance guard: VoiceOver callbacks during notification posting
       can trigger redisplay, which calls ns_update_end, which calls us