Thin Windows runtime globals and legacy GLFW hooks

docs/modernization/roadmap.md

@@ -70,6 +70,9 @@ What is already real:
 - `pp_app_core`
 
 Latest slice:
+- `src/platform_windows/windows_runtime_shell.cpp` no longer keeps a separate
+  retained `AppRuntime*` binding; the touched Windows shell and platform
+  helpers now derive runtime ownership directly from the owned `App`.
 - `src/platform_windows/windows_runtime_shell.cpp` now explicitly owns the
   Windows `App` lifetime through a retained `std::unique_ptr<App>` instead of
   raw `new`/`delete` plus shutdown-side manual cleanup in the lifecycle shell.
@@ -79,6 +82,10 @@ Latest slice:
 - `src/platform_windows/windows_window_shell.cpp` now routes the touched
   key-map and VR-state reads through narrow helpers instead of keeping the
   broader retained-state bundle live across the main window-proc body.
+- `src/platform_legacy/legacy_platform_state.*` no longer exposes the mutable
+  retained GLFW hook bundle; Linux/Web fallback render-context/present/close
+  calls now go through narrow GLFW helper functions instead of an exported hook
+  struct.
 - `scripts/automation/quiet-validate.ps1` is now the bundled checkpoint path
   for Windows build/test plus optional platform and Apple remote validation,
   with one compact JSON summary under `out/logs/quiet-validation`.