Introduces a new 'customFiles' array in the config schema for granular domain-level CSS and JavaScript customization. Updates webserver logic to inject custom CSS/JS tags based on template scope, replacing static custom.css/custom.js references in all Handlebars views. Also updates meshctrl.js to support the new config property.
* Add initial support for custom stylesheets
Allow an override file `custom.css` that can partially override the
stylesheet used for the web interface.
# Changes
1. Update default views to use custom stylesheet
2. Update documentation
Related to: https://github.com/Ylianst/MeshCentral/issues/7144
* Add custom style support to more views
Load `custom.css` in the following views:
- agentinvite.handlebars
- invite.handlebars
- login2.handlebars
- message2.handlebars
- messenger.handlebars
- player.handlebars
- sharing.handlebars
