add activationscript for jellyfin directory

modules/services/jellyfin.nix

@@ -18,6 +18,18 @@
         upstreams = [{ dial = "localhost:8096"; }];
       }];
     }];
+
+    # Create videos directory, allow anyone in Jellyfin group to manage it
+    system.activationScripts.jellyfin = let videosDirectory = "/var/videos";
+    in {
+      text = ''
+        if [ ! -d "${videosDirectory}" ]; then
+          $DRY_RUN_CMD mkdir --parents $VERBOSE_ARG ${videosDirectory}
+          $DRY_RUN_CMD chmod 775 $VERBOSE_ARG ${videosDirectory}
+        fi
+      '';
+    };
+
   };
 
 }