sampathsl/Article-URL-ext — reverse-engineered prompt

Build me a small Liferay ext plugin for journal articles. I want it to change the stored journal article content so every article gets an extra URL element added into the article XML.

The added part should look like a normal Liferay dynamic element named URL, with type text, keyword indexing, index 1, language id en_US, and the value placeholder {URL}. It should append this without breaking the existing article content or removing any other fields.

Please set up the Java code and project files so it can be built and deployed as a Liferay ext plugin. Keep it simple and focused on this one behavior. If there are Liferay version details you need, infer the safest approach from the existing project structure and look up current docs online if needed. Make sure the plugin builds cleanly and include a short README telling me how to build and deploy it.