feat(xonsh): set up ssh-agent

hosts/shared/river.nix

@@ -37,13 +37,14 @@ in {
     environment.systemPackages = builtins.attrValues {
       inherit
         (pkgs)
-        slurp
-        grim
         wf-recorder
         rofi-wayland
         kitty
         wl-clipboard
         ;
+      flameshot = pkgs.flameshot.override {
+        enableWlrSupport = true;
+      };
     };
 
     services.gnome.gnome-keyring.enable = true;