Bind Win32 tablet state in runtime shell

docs/modernization/roadmap.md

@@ -92,6 +92,14 @@ Current hotspot files:
 
 Latest slice:
 
+- The Win32 stylus and pointer-input path no longer reaches
+  `WacomTablet::I` directly inside
+  `src/platform_windows/windows_window_shell.cpp` or
+  `src/platform_windows/windows_stylus_input.cpp`; the live Windows runtime
+  shell now binds the active tablet explicitly through
+  `src/platform_windows/windows_runtime_shell.*`, leaving
+  `WacomTablet::I` only at the entry composition edge where the runtime shell
+  binds the active tablet instance.
 - The remaining dense Windows bootstrap singleton pocket moved off
   `App::I`: `setup_exception_handler(...)`, `initialize_main_window_startup_state(...)`,
   and `_pre_call_callback(...)` now use explicit app/bound-runtime state