Safer monitor lifetimes and clearer driver replies

The latest retained Virtual Display Driver work is less visible than adding a new display mode, but it affects how reliably the rest of the toolchain can control the driver. The August 31 changes addressed monitor lifetime, mode state and named-pipe command handling.

The monitor changes added explicit context cleanup and protected references while work was using an IddCx monitor object. That helps keep a monitor's resources connected to its actual lifetime instead of assuming the object will remain valid through a changing display configuration.

On the control side, shared state and pipe handles received more careful synchronization. Replies were written through explicit helpers, and queries could return useful error information. A normal WDF device restart replaced the earlier unsafe reload behavior.

Why does that matter in the app? If the driver rejects a request, the control panel needs to know. If a connection closes before its response is delivered, a successful write doesn't necessarily tell us whether the requested change succeeded. The matching control-panel work started handling those replies more deliberately too.

The local driver head and GitLab's default head matched for this review. That establishes which source revision we're discussing. I haven't turned that into a claim that a newly signed Windows package was shipped or that a new hardware test matrix passed during this writing task.

The useful next development step is to validate the paired driver and control panel on Windows: monitor creation and removal, mode changes, restart, command errors and repeated connections. The source changes give us a more defensible foundation for that work, with clearer ownership and better feedback when something goes wrong.