patches: fix 3 blockers — duplicate functions, idx typo, doc cap

BLOCKER fixes:
1. Remove duplicate ns_ax_face_is_selected, ns_ax_selected_overlay_text,
   ns_ax_selected_child_frame_text definitions from patch 0002
   (now defined only in 0007/0008 where they belong)
2. Fix idx → point_idx in accessibilityInsertionPointLineNumber (0002)
3. Remove stale 100K cap reference from documentation (0006)

Architecture fix:
- ns_ax_selected_child_frame_text moved from 0007 to 0008
  (where it logically belongs)

Verified: all 8 patches apply cleanly on fresh emacs HEAD.

patches/0006-doc-add-VoiceOver-accessibility-section-to-macOS-app.patch

@@ -1,4 +1,4 @@
-From 5ddf6227b581bf292fc187a1ebcaf80d2cd4cf2a Mon Sep 17 00:00:00 2001
+From 753c2e18a589d38d70df221fa7490d94bdaba937 Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 12:58:11 +0100
 Subject: [PATCH 6/8] doc: add VoiceOver accessibility section to macOS
@@ -12,7 +12,7 @@ Zoom cursor tracking, ns-accessibility-enabled, known limitations.
  1 file changed, 75 insertions(+)
 
 diff --git a/doc/emacs/macos.texi b/doc/emacs/macos.texi
-index 6bd334f..c4dced5 100644
+index 6bd334f..4825cf9 100644
 --- a/doc/emacs/macos.texi
 +++ b/doc/emacs/macos.texi
 @@ -36,6 +36,7 @@ Support}), but we hope to improve it in the future.
@@ -78,9 +78,9 @@ index 6bd334f..c4dced5 100644
 +
 +@itemize @bullet
 +@item
-+Accessibility text is capped at 100,000 UTF-16 units per window.
-+Buffers exceeding this limit are truncated for accessibility purposes;
-+VoiceOver will announce ``end of text'' at the cap boundary.
++Very large buffers (tens of megabytes) may cause slow initial
++accessibility text extraction.  Once cached, subsequent queries
++are fast.
 +@item
 +Mode-line text extraction handles only character glyphs.  Mode lines
 +using icon fonts (e.g., @code{doom-modeline} with nerd-font icons)