hypr: move session daemons from exec-once to systemd user services

Replace the hl.exec_cmd autostart block with declarative home-manager
services so the desktop shell has proper ordering and lifecycle:

- services.hyprpaper (with settings) for hyprpaper
- services.cliphist for the text/image clipboard watchers
- services.hyprpolkitagent for the polkit agent
- programs.quickshell.systemd for the quickshell shell
- a hand-written systemd.user.services.mako (home-manager has no unit)

All are tied to config.wayland.systemd.target (graphical-session.target),
which start-hyprland already activates. No UWSM required.

home/hypr/default.nix

@@ -18,6 +18,7 @@ in
     ./hyprlock.nix
     ./hypridle.nix
     ./quickshell.nix
+    ./services.nix
   ];
 
   home.packages = with pkgs; [
@@ -25,24 +26,32 @@ in
     grim
     slurp
     wl-clipboard
-    cliphist
     brightnessctl
     jq
 
     # Desktop Environment / Hyprland ecosystem
     hyprpaper
-    hyprpolkitagent
   ];
 
   # Build-time rendered wallpaper
   xdg.dataFile."backgrounds/silicon-volt.png".source = wallpaper;
 
-  # hyprpaper: load the Silicon Volt wallpaper on every output
-  xdg.configFile."hypr/hyprpaper.conf".text = ''
-    preload = ${config.home.homeDirectory}/.local/share/backgrounds/silicon-volt.png
-    wallpaper = ,${config.home.homeDirectory}/.local/share/backgrounds/silicon-volt.png
-    splash = false
-  '';
+  # hyprpaper: load the Silicon Volt wallpaper on every output. The
+  # home-manager module writes hypr/hyprpaper.conf and runs the daemon as a
+  # systemd user service tied to the Wayland session.
+  services.hyprpaper = {
+    enable = true;
+    settings = {
+      splash = false;
+      preload = "${config.home.homeDirectory}/.local/share/backgrounds/silicon-volt.png";
+      wallpaper = [
+        {
+          monitor = "";
+          path = "${config.home.homeDirectory}/.local/share/backgrounds/silicon-volt.png";
+        }
+      ];
+    };
+  };
 
   # Notifications: flat brutalist-glass cards with volt accents
   services.mako = {