refactor: moved nixos modules to dendrite pattern

modules/nixos/programs/tailscale/default.nix

@@ -0,0 +1,10 @@
+{config, ...}: let
+  mod = config.flake.nixosModules;
+in {
+  flake.nixosModules.tailscale = {
+    imports = [
+      mod.tailscale-service
+      mod.tailscale-storage
+    ];
+  };
+}

modules/nixos/programs/tailscale/storage.nix

@@ -0,0 +1,26 @@
+{...}: {
+  flake.nixosModules.tailscale-storage = {
+    config,
+    lib,
+    ...
+  }: let
+    tailscale_data_directory = "/var/lib/tailscale";
+  in {
+    options = {
+      services.tailscale.impermanence.enable = lib.mkOption {
+        type = lib.types.bool;
+        default = config.services.tailscale.enable && config.storage.impermanence.enable;
+      };
+    };
+
+    config = lib.mkIf config.services.tailscale.enable {
+      storage.datasets.replicate."system/root" = {
+        directories."${tailscale_data_directory}" = lib.mkIf config.services.tailscale.impermanence.enable {
+          enable = true;
+          owner.name = "root";
+          group.name = "root";
+        };
+      };
+    };
+  };
+}

modules/nixos/programs/tailscale/tailscale.nix

@@ -0,0 +1,21 @@
+{...}: {
+  flake.nixosModules.tailscale-service = {
+    config,
+    lib,
+    ...
+  }: {
+    options = {
+      host.tailscale = {
+        enable = lib.mkEnableOption "should tailscale be enabled on this computer";
+      };
+    };
+
+    config = lib.mkIf config.services.tailscale.enable (
+      lib.mkMerge [
+        {
+          # any configs we want shared between all machines
+        }
+      ]
+    );
+  };
+}