feat: Allow specifying host and port for dev servers

- Updated `dev()` methods in Docusaurus and Starlight to accept
  host and port arguments, defaulting to `localhost:3000`.
- This allows more flexibility in development server setup.
- Updated example scripts to use the new parameters.

examples/web/starllight_example.vsh

@@ -14,4 +14,4 @@ mut site := docs.get(
 	init: true // init means we put config files if not there
 )!
 
-site.dev()!
+site.dev(host: 'localhost', port: 3000)!