vertico: enable buffer-mode for VoiceOver accessibility

Vertico default renders candidates via overlay before-string which
is invisible to the nsterm.m AX text extraction.  vertico-buffer-mode
renders in a real buffer window that the accessibility layer handles.

config.el

@@ -785,6 +785,17 @@ Skip for beamer exports — beamer uses adjustbox on plain tabular."
     '(message-cited-text-4 :foreground "#44475a" :italic t)))
 
 
+;;; ============================================================
+;;; VERTICO — Accessibility
+;;; ============================================================
+
+;; Render candidates in a real buffer window so VoiceOver can read them.
+;; Default Vertico uses overlay before-string which is invisible to the
+;; AX text extraction layer in nsterm.m.
+(after! vertico
+  (vertico-buffer-mode 1))
+
+
 ;;; ============================================================
 ;;; RSS — ELFEED
 ;;; ============================================================