start refactoring shared code into modules, update the lock, do some other minor fixes

modules/nixos/shared-packages/server-settings/jellyfin/default.nix

@@ -0,0 +1,20 @@
+{...}: {
+  services.nginx = {
+    virtualHosts = {
+      "video.gladtherescake.eu" = {
+        forceSSL = true;
+        enableACME = true;
+        locations."/" = {
+          proxyPass = "http://localhost:8096";
+          proxyWebsockets = true; # needed if you need to use WebSocket
+        };
+      };
+    };
+  };
+
+  services.jellyfin = {
+    enable = true;
+    user = "nextcloud";
+    group = "nextcloud";
+  };
+}