Add preview script

An opinionated wrapper around Browsersync.

modules/scripts/preview.nix

@@ -0,0 +1,24 @@
+{
+  flake.modules.homeManager.base =
+    { pkgs, ... }:
+    {
+      home.packages = [
+        (pkgs.writeShellApplication {
+          name = "preview";
+
+          runtimeInputs = with pkgs.nodePackages; [ browser-sync ];
+
+          text = ''
+            # Based on https://github.com/rwxrob/dot/blob/main/scripts/preview.
+
+            browser-sync start \
+              --ignore '**/.*' \
+              --no-notify \
+              --no-open \
+              --no-ui \
+              -sw
+          '';
+        })
+      ];
+    };
+}