patches: auto-detect Zoom/VoiceOver; single variable gates both

Changes:
- EmacsApp gets ns_update_accessibility_state and
  ns_accessibility_did_change: methods (patch 0005)
- At startup: UAZoomEnabled() + AXIsProcessTrustedWithOptions()
  determine initial ns_accessibility_enabled state
- com.apple.accessibility.api distributed notification updates it
  whenever any AT connects or disconnects
- All Zoom call sites (UAZoomChangeFocus) now gated by
  ns_accessibility_enabled in addition to ns_zoom_enabled_p()
- ns-accessibility-enabled docstring updated to describe auto-detect

Result: zero config needed; zero overhead when no AT is active;
single variable overrides auto-detection when needed.

patches/0000-ns-integrate-with-macOS-Zoom-for-cursor-tracking.patch

@@ -1,4 +1,4 @@
-From 38bbd275736251862f4b2fb433ee0a84799f0cec Mon Sep 17 00:00:00 2001
+From d494967af08ec3e5bb94ff50126c2994505a6d85 Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 22:39:35 +0100
 Subject: [PATCH 1/9] ns: integrate with macOS Zoom for cursor tracking