refactor: move persistence into modules where possible

modules/services/kdeconnect.nix

@@ -15,6 +15,10 @@ in
   options.my.services.kdeconnect.enable = mkEnableOption "kdeconnect";
 
   config = mkIf cfg.enable {
+    environment.persistence."/persist".users.moritz.directories = [
+      ".config/kdeconnect"
+    ];
+
     home-manager.users.moritz.services.kdeconnect.enable = mkIf (!config.my.programs.gnome.enable) true;
     networking.firewall = {
       allowedTCPPortRanges = [ ports ];

modules/services/mullvad.nix

@@ -12,6 +12,14 @@ in
   options.my.services.mullvad.enable = mkEnableOption "mullvad";
 
   config = lib.mkIf cfg.enable {
+    environment.persistence."/persist" = {
+      directories = [
+        "/etc/mullvad-vpn/"
+      ];
+      users.moritz.directories = [
+        ".config/Mullvad VPN/"
+      ];
+    };
     services.mullvad-vpn.enable = true;
     users.users.moritz.packages = with pkgs; [
       mullvad-vpn

modules/services/synology-drive.nix

@@ -15,6 +15,11 @@ in
   };
 
   config = mkIf cfg.enable {
+    environment.persistence."/persist".users.moritz.directories = [
+      ".SynologyDrive/data"
+      ".SynologyDrive/log"
+    ];
+
     systemd.user.services.synology-drive = {
       after = [ "graphical-session.target" "network.target" ];
       partOf = [ "graphical-session.target" ];