Add plg_system_mokosuiteclient_backup — detects MokoSuiteBackup and
collects backup status for heartbeat payloads to MokoSuiteHQ.
Scaffolding includes manifest, service provider, extension class,
and language files. Table column names are placeholders pending
MokoSuiteBackup schema confirmation (MokoSuiteBackup#47).
All Joomla element names, PHP classes, language files, folder structure,
and manifest references renamed from mokosuite to mokosuiteclient.
This repo is now the client-facing tracker for the MokoSuite platform.