Refactor DMS IPC bindings for Niri and Hyprland

- Updated `binds.nix` files for both Niri and Hyprland to utilize a centralized `dmsIpcBinds` structure, improving maintainability and consistency across keybindings.
- Introduced `dmsIpcBinds` in `default.nix` for both modules to streamline the command definitions for DMS IPC calls.
- Enhanced `dms` module to define shared IPC commands, ensuring uniform command formatting for different compositors.

modules/desktop/shells/dms/default.nix

@@ -46,4 +46,25 @@
   };
 
   flake.homeManagerModules.desktopShellDms = import ./_private/hm.nix;
+
+  # DMS IPC commands shared between Niri and Hyprland keybind tables.
+  # Defines flake.lib.dmsIpcBinds so each compositor formats the same
+  # command string in its native shape — Niri attrs vs Hyprland string-list.
+  # Adding a new DMS keybind requires editing this file plus the
+  # per-compositor bind layout, not the command string.
+  flake.lib.dmsIpcBinds = {
+    spotlight         = "dms ipc call spotlight toggle";
+    clipboard         = "dms ipc call clipboard toggle";
+    notepad           = "dms ipc call notepad toggle";
+    notifications     = "dms ipc call notifications toggle";
+    processlist       = "dms ipc call processlist toggle";
+    # Hyprland prefers focusOrToggle (window-aware); niri subscribes to toggle.
+    processlistFocus  = "dms ipc call processlist focusOrToggle";
+    settingsFocus     = "dms ipc call settings focusOrToggle";
+    barToggle         = ''dms ipc call bar toggle name "Main Bar"; dms ipc call bar toggle name "Bar 2"'';
+    barToggleBar2     = ''dms ipc call bar toggle name "Bar 2"'';
+    ephemera          = "dms ipc call ephemera toggle";
+    wallpaperCarousel = "dms ipc call wallpaperCarousel toggle";
+    lock              = "dms ipc call lock lock";
+  };
 }