v2.3.0

v2.3.0 - Update System

New update system using electron-updater with GitHub releases integration.

Features:
- Automatic update check 5 seconds after app launch (production only)
- UpdateSidebarBanner component in sidebar
- Download/Install buttons with progress tracking
- NsisUpdater with GitHub publish configuration

Components added:
- src/main/update-manager.ts - Centralized update state management
- src/renderer/src/components/update-sidebar-banner.tsx - Update UI banner