feat: enhance dynamic tool management with notifications and enable/disable

Summary

Enhance the Python SDK's dynamic tool management capabilities to match the TypeScript SDK by adding:

1. Automatic tools/list_changed notifications when tools are added/removed
2. Tool enable/disable functionality (temporary hiding without removal)

Background

The Python SDK currently supports adding and removing tools dynamically (see #1322), but lacks two key features present in the TypeScript SDK:

1. List Changed Notifications

The TypeScript SDK automatically sends notifications/tools/list_changed when tools are modified. This allows clients to know when they should refresh their tool list.

Python SDK gap: Currently, when calling add_tool() or remove_tool(), clients are not notified of the change and may show stale tool lists.

2. Enable/Disable Tools

The TypeScript SDK provides enable() and disable() methods on tools:

const tool = server.tool("myTool", ..., async () => { ... });
tool.disable()  // Hides from list_tools, blocks calls
tool.enable()   // Re-enables the tool
tool.remove()   // Permanently removes

Benefits:

• Temporarily hide tools without losing registration
• Re-enable tools without re-registering
• Useful for permission-based or state-based tool visibility

Python SDK gap: Only permanent removal via remove_tool() is supported. No way to temporarily disable/re-enable tools.

References

• Related PR: #1322 (adds remove_tool method)
• TypeScript SDK Dynamic Servers: https://github.com/modelcontextprotocol/typescript-sdk#dynamic-servers
• MCP spec supports notifications/tools/list_changed

まず、add_tool()、remove_tool()、list_tools()、およびツール呼び出しに対応する Python SDK のエントリーポイントを確認し、その動作を参照先の TypeScript SDK の dynamic-server 実装と比較します。追加および削除されたツールが tools/list_changed 通知をトリガーし、無効化されたツールが非表示かつブロックされ、再度有効化でき、引き続き削除可能であれば完了です。