Feature: Add Pixel Statistics Panel

[cd33]

This PR introduces a new Pixel Statistics feature that provides detailed insights about the current frame and layer in the sprite editor. The new statistics panel includes:

Key Features:

• Real-time pixel statistics tracking
• Display of total pixels in the current frame
• Count and percentage of used (non-transparent) pixels
• Transparency percentage calculation
• Color usage breakdown with:
  • Total number of unique colors
  • Individual color statistics with usage percentages
  • Visual color swatches for each used color
  • Improved ergonomics by allowing users to adjust the size of the panels to suit their needs

Technical Implementation:

• Added new PixelStatsController and PixelStatsService for managing statistics
• Implemented efficient caching mechanism for performance optimization
• Responsive updates on various editor events (frame changes, layer modifications, selections, etc.)
• Clean UI integration with existing toolbox layout

This feature helps artists better understand their sprite composition and color usage patterns, making it easier to optimize sprites and maintain consistent color schemes.