feat: remove unused voxtype dictation feature

Voxtype voice-typing was a full feature (5 scripts, a waybar widget, a
keybind, and a NixOS option) that this install does not use. The
nomarchy.system.voxtype option had no consumer — nothing read it — so the
widget and SUPER+CTRL+X bind were never actually gated by it.

Removes the scripts, default config, the SUPER+CTRL+X bind, the waybar
module (main + summer-night theme + css), the dead option, the installer
comment, and the docs. SCRIPTS.md/KEYBINDINGS.md regenerated; OPTIONS.md
and SKILL.md hand-updated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

installer/install.sh

@@ -1740,9 +1740,6 @@ $xkb_variant_line
   # fcitx5 input method (CJK / IME).
   # nomarchy.system.inputMethod.enable = true;
 
-  # voxtype voice-typing wiring (you must install voxtype yourself).
-  # nomarchy.system.voxtype.enable = true;
-
   system.stateVersion = "25.11";
 }
 EOF