feat: Implement Sprint 3 Part 2 - Toast Notifications and Upload History

[Co0ob1iee]

Toast Notification System:

• Created ToastNotification control with modern design
• Support for 4 types: Success, Info, Warning, Error
• Smooth slide-in/slide-out animations with CubicEase
• Auto-hide timer (configurable duration)
• Custom icons and colors per notification type
• Close button with hover effects
• Drop shadow for professional look

ToastNotificationManager Service:

• Singleton manager for centralized toast handling
• Stack-based toast positioning (max 5 toasts)
• Automatic repositioning when toasts close
• Fallback to standalone window if container not initialized
• Grid-based container support for in-app toasts
• Methods: ShowSuccess, ShowInfo, ShowWarning, ShowError

Replaced Balloon Tips:

• Updated ScreenshotOverlay.xaml.cs to use ToastNotificationManager
• Updated ScreenshotManager.cs upload notifications
• Replaced all TrayIconManager.ShowNotification() calls
• Modern in-app notifications instead of system balloon tips

Upload History Window:

• Complete history of cloud uploads (last 100)
• Display: Index, URL, Filename, Provider, Status
• Color-coded status indicators
• Actions per upload:
  • Copy URL to clipboard
  • Re-upload to cloud
  • Open URL in browser
• Click URL to copy (with toast notification)
• Empty state when no uploads
• Real-time status updates

Features:

• Re-upload functionality with progress feedback
• Error handling with toast notifications
• Automatic URL clipboard copy on re-upload success
• Provider and status tracking
• Chronological sorting (newest first)

Menu Integration:

• Added "Historia uploadów" to tray icon menu
• Accessible via TrayIconManager context menu
• Shows UploadHistoryWindow on click

Technical Implementation:

• ObservableCollection for dynamic UI updates
• DataTemplate for upload item rendering
• Async re-upload with await pattern
• BitmapImage loading from file path
• Process.Start for browser opening
• Toast notifications for user feedback

This completes Sprint 3 notification and upload tracking features as outlined in docs/planning/sprint-3-tasks.md