Adds a new 'CSS Variables' tab to the template configuration with eight
documented sections (brand, typography, navigation, header background,
container backgrounds, borders/shadows, forms/focus) so site builders
can reference all available custom properties without leaving Joomla admin.
Also removes external docs links from descriptions in templateDetails.xml
and both language files, replacing them with a pointer to the new tab.
Fixes stale custom palette source paths in en-GB and en-US ini files.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Jonathan Miller
e6a0a0a81e