fix(#640): correctly nest contact group when init has nested groups

[Hendrixx-RE]

Description

fixed a bug in the contact form conversion logic that was causing /data/contact groups to be nested incorrectly when the form had other nested groups.

fixes #640

Replaced the Regular Expression based nesting logic in src/fn/convert-contact-forms.js with a DOM-based approach using DOMParser.

1. Imports: Added DOMParser and XMLSerializer from the @xmldom/xmldom package.
2. Logic: Instead of using a string-based search-and-replace, the code now:
   • Parses the form XML into a searchable document tree.
   • Explicitly finds the group nodes with ref="/data/contact" and ref="/data/init".
   • Moves the contact group to be a direct child at the end of the init group.

Code review items

• Readable: Concise, well named, follows the style guide, documented if necessary.
• Documented: Configuration and user documentation on cht-docs
• Tested: Unit and/or integration tests where appropriate
• Backwards compatible: Works with existing data and configuration. Any breaking changes documented in the release notes.

License

The software is provided under AGPL-3.0. Contributions to this project are accepted under the same license.