AJAX-powered file browser in backups list and detail views:
- AjaxController::browseArchive() reads ZIP/tar.gz entries
- Browse button on each backup row + detail view
- Modal shows file list with names and sizes (first 500 entries)
Closes#59
Renames all sub-extensions from mokojoombackup to mokosuitebackup
(package, component, 7 plugins, language files, manifests).
Adds [HOME] placeholder to BackupDirectory and PlaceholderResolver
so users can set backup_dir to [HOME]/backups (outside web root).
Fixes folder browser "access denied" on PHP-FPM shared hosting
where getenv('HOME') returns empty by adding POSIX and JPATH_ROOT
fallback detection.