feat(menu): group the rofi picker into Tools / System submenus

The root picker had grown to 16 flat entries. Collapse it to six —
Apps · Theme · Tools › · System › · Power · Keybindings — with Tools
(Calculator, Clipboard, Emoji, Files, Web, Capture, Ask) and System
(Network, Bluetooth, DND, plus the self-gated Snapshots / Power-profile)
as submenus the dispatcher routes via `nomarchy-menu tools|system`. Each
submenu ends in a ← Back entry that re-opens the root. The direct
SUPER+CTRL+<mnemonic> binds still reach the leaves straight (bypassing
the menu), and the gated entries still hide when unavailable.

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

modules/home/rofi.nix

@@ -180,54 +180,78 @@ let
           || { notify-send "Snapshots" "btrfs-assistant isn't installed (BTRFS snapshots off?)."; exit 0; }
         exec btrfs-assistant ;;
 
-      "")
+      tools)
+        # Tools submenu — utilities you invoke. Each leaf is also reachable
+        # directly (SUPER+CTRL+<mnemonic>); this just keeps the root short.
+        choice=$(printf '%s\n' \
+          "󰃬  Calculator" \
+          "󰅌  Clipboard" \
+          "󰒨  Emoji" \
+          "󰈞  Files" \
+          "󰖟  Web search" \
+          "󰄄  Capture" \
+          "󰭹  Ask Claude" \
+          "󰁍  Back" \
+          | rofi -dmenu -p tools) || exit 0
+        case "$choice" in
+          *Calc*)      exec "$0" calc ;;
+          *Clipboard*) exec "$0" clipboard ;;
+          *Emoji*)     exec "$0" emoji ;;
+          *Files*)     exec "$0" files ;;
+          *Web*)       exec "$0" web ;;
+          *Capture*)   exec "$0" capture ;;
+          *Ask*)       exec "$0" ask ;;
+          *Back*)      exec "$0" ;;
+        esac ;;
+
+      system)
+        # System submenu — connectivity and machine state. Snapshots and the
+        # power-profile picker self-gate (BTRFS+snapper / laptop on ppd), so
+        # the submenu shrinks to match the hardware, like the Waybar modules.
         entries=(
-          "󰀻  Apps"
-          "󰏘  Theme"
-          "󰅌  Clipboard"
-          "󰃬  Calculator"
-          "󰈞  Files"
-          "󰒨  Emoji"
-          "󰖟  Web search"
           "󰖩  Network"
           "󰂯  Bluetooth"
-          "󰄄  Capture"
-          "󰋖  Keybindings"
-          "󰭹  Ask Claude"
           "󰂛  Do Not Disturb"
         )
-        # Snapshots only when btrfs-assistant is installed (BTRFS + snapper).
         command -v btrfs-assistant >/dev/null 2>&1 && entries+=("󰋚  Snapshots")
-        # Power-profile picker only when this is a laptop (battery present)
-        # running power-profiles-daemon — matches the Waybar indicator's
-        # self-gating; desktops and the TLP backend don't show it.
         bats=(/sys/class/power_supply/BAT*)
         if [ -e "''${bats[0]}" ] && command -v powerprofilesctl >/dev/null 2>&1; then
           entries+=("󰓅  Power profile")
         fi
-        entries+=("󰐥  Power")
-        choice=$(printf '%s\n' "''${entries[@]}" | rofi -dmenu -p menu) || exit 0
+        entries+=("󰁍  Back")
+        choice=$(printf '%s\n' "''${entries[@]}" | rofi -dmenu -p system) || exit 0
         case "$choice" in
-          *Apps*)      exec rofi -show drun ;;
-          *Theme*)     exec "$0" theme ;;
-          *Clipboard*) exec "$0" clipboard ;;
-          *Calc*)      exec "$0" calc ;;
-          *Files*)     exec "$0" files ;;
-          *Emoji*)     exec "$0" emoji ;;
-          *Web*)       exec "$0" web ;;
-          *Network*)   exec "$0" network ;;
-          *Bluetooth*) exec "$0" bluetooth ;;
-          *Capture*)   exec "$0" capture ;;
-          *Keybindings*) exec "$0" keybinds ;;
-          *Ask*)       exec "$0" ask ;;
+          *Network*)          exec "$0" network ;;
+          *Bluetooth*)        exec "$0" bluetooth ;;
           *"Do Not Disturb"*) exec "$0" dnd ;;
-          *Snapshots*) exec "$0" snapshot ;;
-          *"Power profile"*) exec "$0" power-profile ;;
-          *Power*)     exec "$0" power ;;
+          *Snapshots*)        exec "$0" snapshot ;;
+          *"Power profile"*)  exec "$0" power-profile ;;
+          *Back*)             exec "$0" ;;
+        esac ;;
+
+      "")
+        # Root picker — grouped into category submenus so the top level stays
+        # short and scannable. Apps/Theme/Power/Keybindings are frequent enough
+        # to keep at the top; everything else lives under Tools or System.
+        choice=$(printf '%s\n' \
+          "󰀻  Apps" \
+          "󰏘  Theme" \
+          "󰦬  Tools" \
+          "󰒓  System" \
+          "󰐥  Power" \
+          "󰋖  Keybindings" \
+          | rofi -dmenu -p menu) || exit 0
+        case "$choice" in
+          *Apps*)        exec rofi -show drun ;;
+          *Theme*)       exec "$0" theme ;;
+          *Tools*)       exec "$0" tools ;;
+          *System*)      exec "$0" system ;;
+          *Power*)       exec "$0" power ;;
+          *Keybindings*) exec "$0" keybinds ;;
         esac ;;
 
       *)
-        echo "usage: nomarchy-menu [power|power-profile|theme|clipboard|calc|files|emoji|web|network|bluetooth|capture|keybinds|ask|dnd|snapshot]" >&2
+        echo "usage: nomarchy-menu [tools|system|power|power-profile|theme|clipboard|calc|files|emoji|web|network|bluetooth|capture|keybinds|ask|dnd|snapshot]" >&2
         exit 64 ;;
     esac
   '';