feat: add proxy for native Gyazo MCP server tools

[yuiseki]

This pull request introduces native screen capture and upload functionality for Gyazo on Windows and macOS, integrating it into the existing toolset. The changes include a new module for managing the native MCP server, updates to the tool handlers to support capture-related operations, and enhancements to ensure graceful shutdown of resources.

New Native Capture Integration

• New GyazoNativeMCPServer class: Added a singleton class in src/capture-proxy.ts to manage the lifecycle of the native MCP server, including initialization, request handling, and cleanup. It supports operations such as listing capturable windows, capturing the primary screen, capturing a selected region, and capturing a specific window.

Tool Handler Updates

• Tool registration and availability checks: Updated the listToolsHandler in src/handlers/tools.ts to dynamically include native capture tools if the MCP server is available. These tools allow users to perform screen capture operations and upload results to Gyazo. [1] [2]
• New tool handlers: Added handlers for native capture tools (gyazo_list_capturable_windows, gyazo_capture_and_upload_primary_screen, gyazo_capture_and_upload_region, and gyazo_capture_and_upload_window) to process requests and interact with the MCP server. [1] [2]

Graceful Shutdown Enhancements

• Cleanup handlers: Added cleanup logic in src/index.ts to ensure the MCP server is properly shut down during application termination (e.g., on SIGINT, SIGTERM, or process exit).

Type Definitions

• New types for capture operations: Defined CapturableWindow and CaptureUploadResponse types in src/types.ts to standardize data structures for capturable windows and capture responses.