v2.6.2 (Lyra): Thema editor, content editor, unified scanEditorFiles

- Thema editor (thema's net zo bewerkbaar maken als plugins):
  bestandsbrowser zijbalk, nieuw bestand, uploaden, verwijderen,
  verplaatsen, SCSS compileren vanuit editor, thema activeren/
  verwijderen, nieuw thema met basis-kopie, uniforme thema-structuur
- Content editor (content consistent met plugins en thema's):
  bestandsbrowser zijbalk naast bestaande lijst weergave, nieuw
  bestand/map, uploaden, verwijderen, verplaatsen, mappen beheer,
  layout/plugins selectie, git/backup integratie in editor zijbalk
- Uniformiteit: scanEditorFiles() unified scanner
  (scanPluginFiles/scanThemeFiles/scanContentFiles als dunne wrappers)
- Media invoegen in editor: ?theme= scope voor media-list endpoint
- Bug fix: thema-naam niet overgenomen bij kopiëren - title in
  theme.json wordt overschreven met nieuwe themanaam
- Handleidingen bijgewerkt (thema-beheer.md + content-beheer.md NL/EN)
- Release notes: docs/release-notes/v2.6.2.md
- Pentest 30/30, WCAG 25/25

admin/src/AdminAuth.php

@@ -16,9 +16,9 @@ class AdminAuth
      */
     public const ROLE_PERMISSIONS = [
         'admin' => ['*'],
-        'content-manager' => ['dashboard', 'content', 'content-edit', 'content-new', 'content-delete', 'content-dir-create', 'content-dir-rename', 'content-dir-delete', 'content-move', 'content-backup', 'content-restore', 'content-git-init', 'content-git-commit', 'content-git-restore', 'guide', 'logout'],
+        'content-manager' => ['dashboard', 'content', 'content-files', 'content-edit', 'content-new', 'content-delete', 'content-file-upload', 'content-file-delete', 'content-file-move', 'content-dir-create', 'content-dir-create-in', 'content-dir-rename', 'content-dir-rename-in', 'content-dir-delete', 'content-dir-delete-in', 'content-move', 'content-backup', 'content-restore', 'content-git-init', 'content-git-commit', 'content-git-restore', 'guide', 'logout'],
         'bi-manager' => ['dashboard', 'statistics', 'logs', 'guide', 'logout'],
-        'site-admin' => ['dashboard', 'theme', 'theme-new', 'plugins', 'plugins-new', 'plugins-edit', 'plugins-config', 'plugins-toggle', 'plugins-delete', 'statistics', 'logs', 'update', 'guide', 'logout'],
+        'site-admin' => ['dashboard', 'theme', 'theme-new', 'theme-edit', 'theme-file-upload', 'theme-file-delete', 'theme-file-move', 'theme-activate', 'theme-delete', 'theme-scss', 'plugins', 'plugins-new', 'plugins-edit', 'plugins-config', 'plugins-toggle', 'plugins-delete', 'statistics', 'logs', 'update', 'guide', 'logout'],
     ];
 
     /**