[arshcaria]

Summary

Fixes #198.

A taskbar-hosted surface is a child of Shell_TrayWnd. DefWindowProc forwards several mouse messages from a child window to its parent with a synchronous SendMessage, so the widget was making blocking calls into Explorer's taskbar thread:

• WM_MOUSEACTIVATE on every button press. A hang dump of explorer.exe showed the Taskbar thread stuck in UI Automation while handling exactly this message (sent to Shell_TrayWnd from a right-button press). The monitor's UI thread waited on it until the hang watchdog relaunched the widget, or Windows restarted Explorer.
• WM_SETCURSOR on every mouse move over a non-clickable area, through the set_surface_cursor(...) == false fallback.
• Wheel and WM_APPCOMMAND messages.

Changes:

• Both surface window procedures return MA_NOACTIVATE for WM_MOUSEACTIVATE. The surfaces are WS_EX_NOACTIVATE and never activate, and the click itself is still delivered.
• set_surface_cursor always sets a cursor (hand over clickable layers, arrow elsewhere), and WM_SETCURSOR returns TRUE without DefWindowProc.
• WM_MOUSEWHEEL, WM_MOUSEHWHEEL, WM_APPCOMMAND and WM_CONTEXTMENU are consumed by the surfaces, which have no handlers for them.
• The widget tooltip is now owned by the controller instead of the surface. A popup owned by a child window is owned by that child's top-level ancestor, which put the tooltip in Explorer's Shell_TrayWnd owner chain.

Testing

• cargo fmt --all -- --check: passes
• cargo test --locked: 603 passed, 6 ignored. The run includes a new regression test, hosted_surface_never_forwards_mouse_messages_to_its_parent. It first confirms that DefWindowProc forwards WM_MOUSEACTIVATE to a recording parent, then checks that the surface wnd_proc forwards none of these messages.
• cargo build --locked --release: succeeds
• Manual check: confirmed at runtime that the tooltip's owner is the controller window (GetWindow(GW_OWNER)), not Shell_TrayWnd. The hang is intermittent and appeared roughly once per handful of right-clicks over an evening on the affected machine. I am running this build there now and will report back on the issue.

Checklist

• I have read CONTRIBUTING.md and CODE_OF_CONDUCT.md.
• The change is focused and contains no credentials or sensitive data.
• I have added or updated relevant documentation and tests, where applicable.
• I have left changelog and version changes to maintainers unless requested.

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