feat(dnd): swaync Do-Not-Disturb toggle + Waybar bell indicator

Adds a Do-Not-Disturb story on top of swaync:

- Waybar `custom/notification` module via `swaync-client -swb` — streams
  the notification count + DND state (no polling). Left-click toggles the
  panel, right-click toggles DND; bell-off glyph + muted color when DND is
  on, accent when notifications are waiting.
- `nomarchy-menu dnd` toggle in the root picker and bound to SUPER+CTRL+D
  (so it shows in the SUPER+? cheatsheet). Turning DND off confirms with a
  toast; turning it on is silent — notifications are suppressed and the
  bell-off icon is the cue.

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

docs/ROADMAP.md

@@ -236,9 +236,13 @@ how to override it. Items marked ✓ are shipped.
   bind (`hyprctl switchxkblayout` / xkb `grp:` options) and a Waybar
   indicator for the active layout. Natural follow-on to the LUKS-keymap work
   — keep the system (console/initrd) and session layouts in sync.
-- **Do-Not-Disturb:** a swaync DND toggle (`swaync-client -dn`) wired into
-  the menu and a Waybar indicator, to silence notifications for
-  presentations/focus.
+- ✓ **Do-Not-Disturb:** swaync DND toggle wired into the menu
+  (`nomarchy-menu dnd`, in the picker, SUPER+CTRL+D) and a Waybar bell
+  indicator (`custom/notification` via `swaync-client -swb`: shows the
+  notification count + DND state, left-click toggles the panel,
+  right-click toggles DND). Turning DND off confirms with a toast; turning
+  it on is silent (notifications are suppressed — the bell-off glyph is the
+  cue).
 - **Snapshot browse/restore UX:** snapper already takes BTRFS timeline
   snapshots (`nomarchy.system.snapper`); surface them from the desktop — a
   rofi menu (or btrfs-assistant) to browse/diff/restore and boot-from-