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

@@ -1,4 +1,4 @@
-From 44cb6c8657feb1e17afabfb1a97d341727245bdd Mon Sep 17 00:00:00 2001
+From e2213409bca76154764263879b4bd43459230d6c Mon Sep 17 00:00:00 2001
 From: Martin Sukany <martin@sukany.cz>
 Date: Sat, 28 Feb 2026 12:58:11 +0100
 Subject: [PATCH 7/9] doc: add VoiceOver accessibility section to macOS