feat: status item right-click context menu support

[JokerRun]

Problem

When using statusItem(), there is no way to attach a native context menu to the status bar icon. Right-clicking (or ctrl-clicking) does nothing.

For agent-driven UIs (e.g. companion panels, monitoring tools), a right-click menu is essential for actions like Quit, Toggle visibility, Open inspector, etc. Without it, users must build these controls inside the popover HTML, which is cumbersome and non-native.

Proposed Solution

Add native NSMenu support for status items:

Swift side:

• Handle rightMouseUp and ctrl+leftMouseUp on the status item button
• Parse a new status-menu JSON command to build NSMenu items dynamically
• Emit {"type":"menu","id":"..."} on stdout when a menu item is selected

Node wrapper:

• Add setMenu(items) method on the GlimpseWindow instance
• Emit 'menu' event with the selected item id

Usage

const menu = statusItem(html, { title: 'My Agent' });

menu.setMenu([
  { id: 'inspect', title: 'Open Inspector' },
  { id: 'quit', title: 'Quit' },
]);

menu.on('menu', (id) => {
  if (id === 'quit') process.exit(0);
});

I have a working implementation and will open a PR shortly.