fix(sway): bind the launcher to Mod+Space

Only `menu` was set, which the module's default keybindings run on Mod+d;
Mod+Space defaulted to `focus mode_toggle`, so sway-launcher-desktop was
never reachable from Mod+Space. Add an explicit Mod+Space -> exec ${menu}
binding at normal priority (via mkMerge) so it overrides the default.
Mod+d still launches it as well.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyrathorpe/home/sway.nix

@@ -55,7 +55,13 @@
         }
       ];
 
-      keybindings = lib.mkOptionDefault (
+      keybindings = lib.mkMerge [
+        # Bind the launcher to Mod+Space. This deliberately replaces the default
+        # Mod+Space (focus mode_toggle); a bare attrset (normal priority) wins
+        # over the module default, whereas the mkOptionDefault block below would
+        # only tie with it. Mod+d still runs the launcher too (module default).
+        { "${modifier}+space" = "exec ${menu}"; }
+        (lib.mkOptionDefault (
           {
             "${modifier}+l" = "exec ${pkgs.swaylock}/bin/swaylock -f";
             "Print" = "exec ${pkgs.grim}/bin/grim ~/screenshot-$(date +%F-%H%M%S).png";
@@ -68,7 +74,8 @@
             "XF86MonBrightnessUp" = "exec ${pkgs.brightnessctl}/bin/brightnessctl set 5%+";
             "XF86MonBrightnessDown" = "exec ${pkgs.brightnessctl}/bin/brightnessctl set 5%-";
           }
-      );
+        ))
+      ];
     };
   };