We need a way (maybe via build-copy script?) to copy index.html and main.js to the webapp directory in the project, so they are available after installing the plugin. With the current config, they need to be copied to src/main/webapp/js/.

Repro:

• run `npm run build-copy` to build the webapp and copy it 
• run `mvn install`
• run a separate jenkins instance not tied to the project
• install the plugin via the jenkins plugin UI
• open the <your jenkins url>/working-hours route

Expected:

• Working hours UI is visible

Actual

• Error: index.html not found