feat: moved ollama, tailscale, and sync into folders following the new storage pattern

modules/nixos-modules/sync/storage.nix

@@ -0,0 +1,57 @@
+{
+  config,
+  lib,
+  ...
+}: let
+  mountDir = "/mnt/sync";
+  configDir = "/etc/syncthing";
+in {
+  options = {
+    services.syncthing.impermanence.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = config.services.syncthing.enable && config.storage.impermanence.enable;
+    };
+  };
+
+  config = lib.mkIf config.services.syncthing.enable (
+    lib.mkMerge [
+      (lib.mkIf config.storage.zfs.enable (lib.mkMerge [
+        {
+          # Syncthing needs persistent storage for configuration and data
+        }
+        (lib.mkIf (!config.services.syncthing.impermanence.enable) {
+          # TODO: placeholder to configure a unique dataset for this service
+        })
+        (lib.mkIf config.services.syncthing.impermanence.enable {
+          assertions =
+            [
+              {
+                assertion = config.services.syncthing.configDir == configDir;
+                message = "syncthing config dir does not match persistence";
+              }
+            ]
+            ++ lib.attrsets.mapAttrsToList (_: folder: {
+              assertion = lib.strings.hasPrefix mountDir folder.path;
+              message = "syncthing folder ${folder.label} is stored at ${folder.path} which not under the persisted path of ${mountDir}";
+            })
+            config.services.syncthing.settings.folders;
+
+          storage.impermanence.datasets."persist/system/root" = {
+            directories = {
+              "${mountDir}" = {
+                enable = true;
+                owner.name = "syncthing";
+                group.name = "syncthing";
+              };
+              "${configDir}" = {
+                enable = true;
+                owner.name = "syncthing";
+                group.name = "syncthing";
+              };
+            };
+          };
+        })
+      ]))
+    ]
+  );
+}