Add tray icon mouse wheel performance mode cycling

[aimagist]

Summary

Adds a convenient shortcut for changing performance modes from the system tray.

When the cursor is over the G-Helper tray icon, scrolling the mouse wheel cycles the current performance mode without opening the main window or context menu:

• Scroll up: next performance mode
• Scroll down: previous performance mode

This uses the existing ModeControl.CyclePerformanceMode() path, preserving the current mode cycling, toast, and delay behavior.

Details

Since WinForms NotifyIcon does not provide a MouseWheel event, this PR adds a small tray wheel handler that listens for mouse wheel messages and only handles them when the cursor is over the G-Helper tray icon.

The handler resolves the tray icon bounds via Shell_NotifyIconGetRect, with a fallback based on the last NotifyIcon.MouseMove position.

The hook is disposed during application exit.

Testing

• dotnet build app/GHelper.sln -c Release -p:Platform=x64 -p:GITHUB_ACTIONS=true
• Manual test on Windows: scrolling over the tray icon successfully cycles between performance modes.