revert(niri): restore pyclipsync for QQ's X11 clipboard

Reverts 9152e829: QQ's Wayland window still copies through the X11 CLIPBOARD, which xwayland-satellite cannot bridge, so QQ copies never reached Wayland apps.

Assisted-by: DeepSeek Harness (claude-opus-5-5)

home/linux/gui/niri/default.nix

@@ -2,12 +2,18 @@
   pkgs,
   config,
   lib,
+  pyclipsync,
   ...
 }@args:
 let
   cfg = config.modules.desktop.niri;
 in
 {
+  imports = [
+    # provides `services.pyclipsync.enable`
+    pyclipsync.homeModules.default
+  ];
+
   options.modules.desktop.niri = {
     enable = lib.mkEnableOption "niri compositor";
   };
@@ -51,6 +57,10 @@ in
           };
         };
 
+        # QQ draws a Wayland window but copies through the X11 CLIPBOARD, which
+        # xwayland-satellite bridges only while an X11 window has focus.
+        services.pyclipsync.enable = true;
+
         # NOTE: this executable is used by greetd to start a wayland session when system boot up
         # with such a vendor-no-locking script, we can switch to another wayland compositor without modifying greetd's config in NixOS module
         home.file.".wayland-session" = {