Add Screenshot Capture API

[great-majority]

This PR introduces a comprehensive screenshot capture system that allows external clients to capture the current Studio view as PNG images via WebSocket.

What's Added

📸 Screenshot Command

• New screenshot command type - Capture current Studio view as PNG image
• Flexible sizing options - Custom width/height or use optimized defaults
• Transparency support - Optional alpha channel for advanced compositing
• Capture mark control - Toggle Studio's capture overlay on/off
• Base64 encoding - Images delivered as JSON-compatible Base64 strings

🔧 Technical Implementation

• Native Studio integration - Uses Studio.GameScreenShot.CreatePngScreen() for high-quality captures
• Multi-camera rendering - Leverages Studio's camera array for complete scene capture
• Memory efficient - Automatic cleanup and resource management
• Error handling - Comprehensive error reporting for failed captures

📏 Optimized Defaults

• 480p default resolution (854x480) - Balanced quality vs. WebSocket size limits
• ~50-100KB typical file sizes - Fits comfortably within WebSocket message limits
• Instant capture - No file I/O, direct memory-to-network transmission

API Usage

// Simple capture (854x480)
{"type": "screenshot"}

// Custom size
{"type": "screenshot", "width": 1920, "height": 1080}

// Advanced options
{
  "type": "screenshot",
  "width": 854,
  "height": 480,
  "transparency": true,
  "mark": false
}

Response Format

{
  "type": "success",
  "message": "Screenshot captured successfully",
  "data": {
    "image": "iVBORw0KGgoAAAANSUhEUg...", // Base64 PNG data
    "width": 854,
    "height": 480,
    "format": "png",
    "transparency": false,
    "size": 67890
  }
}

Benefits

• 🚀 Real-time monitoring - External tools can capture Studio state instantly
• 📱 Remote preview - Build mobile/web interfaces showing current Studio view
• 🎬 Automation workflows - Automated screenshot capture for documentation/testing
• 🔄 Live streaming - Foundation for potential live streaming features
• 💾 Memory efficient - No temporary files, direct network delivery

Documentation

• Comprehensive examples - Both English and Japanese documentation
• Parameter reference - Detailed explanation of all options
• Error handling guide - Common issues and troubleshooting
• Integration examples - Ready-to-use code snippets

This feature opens up new possibilities for external Studio integrations, from simple monitoring tools to sophisticated automation systems that need visual feedback from the
Studio environment.