feat(sway-desktop): set up for screensharing of headless outputs

nix/os/snippets/sway-desktop.nix

@@ -40,6 +40,25 @@ in {
 
     wlr = {
       enable = true;
+      settings = {
+        screencast = {
+          chooser_type = "dmenu";
+          # display the output as a list in favor of the default mouse selection
+          chooser_cmd = lib.getExe (pkgs.writeShellApplication {
+            name = "chooser_cmd";
+            runtimeInputs = [
+              pkgs.sway
+              pkgs.jq
+              pkgs.fuzzel
+              pkgs.gnused
+            ];
+            text = ''
+              swaymsg -t get_outputs | jq '.[] | "\(.name)@\(.current_mode.width)x\(.current_mode.height) on \(.model)"' | sed 's/"//g' | fuzzel -d | sed 's/@.*//'
+            '';
+          });
+          max_fps = 30;
+        };
+      };
     };
 
     # keep the behaviour in < 1.17, which uses the first portal implementation found in lexicographical order, use the following: