Run Sunshine as a service

Goodbye Flatpak Sunshine. Hello AppImage.
Until a deb package is available for Debian Bookworm, we can just run sunshine as an AppImage.
It is faster to startup and is a little less bloated.

The goal here is to run Sunshine as a service managed by supervisord so that it is kept running and is restarted automatically if stopped.

overlay/templates/sunshine/apps.json

@@ -4,11 +4,22 @@
     },
     "apps": [
         {
-            "name": "Steam BigPicture",
-            "output": "steam.txt",
-            "cmd": "",
+            "name": "Desktop",
+            "image-path": "desktop.png",
+            "exclude-global-prep-cmd": "true"
+        },
+        {
+            "name": "Steam Big Picture",
+            "image-path": "steam.png",
+            "exclude-global-prep-cmd": "false",
             "detached": [
                 "\/usr\/games\/steam steam:\/\/open\/bigpicture"
+            ],
+            "prep-cmd": [
+                {
+                    "do": "",
+                    "undo": "\/usr\/bin\/xfce4-close-all-windows"
+                }
             ]
         }
     ]

overlay/templates/sunshine/sunshine.conf

@@ -28,6 +28,10 @@
 #
 min_log_level = info
 
+# A list of commands to be run before/after all applications.
+#   If any of the prep-commands fail, starting the application is aborted.
+global_prep_cmd = [{"do":"/usr/bin/xfce4-minimise-all-windows","undo":"/usr/bin/sunshine-stop"}]
+
 # The origin of the remote endpoint address that is not denied for HTTP method /pin
 # Could be any of the following values:
 #   pc|lan|wan
@@ -95,7 +99,7 @@ min_log_level = info
 # ping_timeout = 10000
 
 # The file where configuration for the different applications that Sunshine can run during a stream
-file_apps = /home/default/sunshine/apps.json
+file_apps = apps.json
 
 # Percentage of error correcting packets per data packet in each video frame
 # Higher values can correct for more network packet loss, but at the cost of increasing bandwidth usage
@@ -111,7 +115,7 @@ file_apps = /home/default/sunshine/apps.json
 #
 # Unlike simply broadcasting to multiple Client, this will generate distinct video streams.
 # Note, CPU usage increases for each distinct video stream generated
-# channels = 1
+channels = 2
 
 # The back/select button on the controller
 # On the Shield, the home and powerbutton are not passed to Moonlight