[VSCode Extension] Add native system/toast notifications when Claude needs attention

Summary

The VSCode native extension currently has no way to notify the user when Claude needs attention (permission approval, task completion, waiting for input). The only indicators are:

• A colored dot on the editor tab (🔵 pending / 🟠 done)
• "✱ Claude Code" text in the status bar

Both are easy to miss when focus is on another window or monitor.

Request

Add a setting to emit VSCode/system-level notifications on key events, e.g.:

• claude-code.notifications.enabled: boolean
• claude-code.notifications.events: array of permissionRequest | taskComplete | waitingForInput | error

Ideally using vscode.window.showInformationMessage so users can rely on VSCode's built-in notification filter / Do Not Disturb.

Why not hooks?

Hooks (Notification / Stop) + external tools (BurntToast, msg, terminal-notifier) work, but:

• Require platform-specific scripting
• Not discoverable for new users
• Duplicate work every user has to redo

A first-class setting would be much more ergonomic.

Environment

• OS: Windows 11
• VSCode native extension