Add system tray context menu with Show/Hide and Quit options

[BP602]

Problem

The system tray icon has no right-click context menu, making it impossible to show/hide the app or quit from the tray. Users expect standard tray functionality.

Expected Behavior

Right-clicking the tray icon should show a context menu with:

• Show/Hide KickTalk - Toggle window visibility
• Quit - Exit the application

Current Behavior

• Right-clicking the tray icon does nothing
• No way to interact with the app from the tray except left-click

Technical Details

In src/main/index.js, the tray is created with:

tray = new Tray(iconPath);
tray.setToolTip("KickTalk");

But there's no tray.setContextMenu() call to add the right-click menu.

Implementation Notes

Need to:

1. Import Menu from electron
2. Create context menu with Show/Hide and Quit options
3. Handle window show/hide state appropriately
4. Set the context menu on the tray instance

Acceptance Criteria

• Right-click tray icon shows context menu
• "Show/Hide KickTalk" toggles window visibility
• "Quit" properly closes the application
• Menu items have appropriate labels and shortcuts

[BP602]

related to #29