Sprint 2 high-priority cleanup: cart/language/location services called
localStorage directly, bypassing the try/catch safety and core/<domain>
pattern used elsewhere (e.g. ProjectEditorDraftStorageService). New
core/storage/LocalStorageService centralizes get/set/remove and JSON
helpers with private-mode/quota error handling, reused across all three.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
