home: wm: i3: use keycode for shutdown mapping

The motivation for using keycodes for all those mappings is to allow
switch to an actual french keyboard layout it still be able to move
through workspaces etc...

home/wm/i3.nix

@@ -243,7 +243,6 @@ in
             # Sub-modes
             "${modifier}+r" = "mode resize";
             "${modifier}+Shift+space" = "mode floating";
-            "${modifier}+0" = ''mode "${shutdownMode}"'';
           }
           (lib.optionalAttrs config.my.home.wm.screen-lock.enable {
             "${modifier}+x" =
@@ -292,6 +291,9 @@ in
           builtins.foldl' (lhs: rhs: lhs // rhs) { } [
             (createWorkspaceBindings modifier "workspace number")
             (createWorkspaceBindings "${modifier}+Shift" "move container to workspace number")
+            {
+              "${modifier}+${toString (toKeycode 0)}" = ''mode "${shutdownMode}"'';
+            }
           ];
 
         modes =