[FIX] Fix admin page language handling for all tiki-admin_* pages

Camilerequested to merge
camilevahviraki/tiki:fix/admin-pages-language into master

Problem

  • Admin pages ignored the admin_language preference and used the default language instead.

Because $section wasn't set before language loading.

Solution

  • Converted Tiki\Sections to singleton pattern

  • Updated all admin pages to use Sections::getInstance()->setCurrentSection()

  • Removed global $section variable dependency

Changes

  • Added section initialization before tiki-setup.php in all admin files
  • Replaced magic strings with class constants
  • Centralized section management using singleton pattern

Result

  • All admin pages now load correct language files
  • Consistent section handling across the application
  • Cleaner architecture without global variables

Related task: https://dev.tiki.org/item8826

Edited by Camile

Merge request reports