Drop dead Win32 retained key state

docs/modernization/tasks.md

@@ -78,6 +78,8 @@ Completed, blocked, and superseded task history moved to
   the queue is now ordered by code movement instead.
 
 Current slice:
+- `src/platform_windows/windows_window_shell.*` no longer keeps the dead
+  retained raw key-state array.
 - `linux/src/main.cpp` now owns the Linux FPS-title callback lifecycle
   directly, and `src/app_events.cpp` no longer installs Linux-specific title
   behavior from `App::set_platform_services()`.