Whats Next? 0.19.0 - CurseForge-safe data separation

- Added Data/ for bundled shared databases updated with addon releases.
- Added UserData/ storage layer.
- New persistent root: WhatsNextUserData for user choices and settings.
- New persistent root: WhatsNextCache for rebuildable client caches.
- Legacy WhatsNextDB is automatically migrated without losing existing data.
- Bundled profession and English-name databases are now clearly versioned
  addon files and therefore update with CurseForge releases.
- User tasks, My Loot, Tank Assistant routes and preferences remain in WTF
  SavedVariables and survive addon updates.
