Move Windows bootstrap off App::I

docs/modernization/roadmap.md

@@ -92,6 +92,13 @@ Current hotspot files:
 
 Latest slice:
 
+- 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
+  instead of reading the app singleton directly in
+  `src/platform_windows/windows_bootstrap_helpers.*`, and the app-side
+  platform dispatch helpers in `src/app_events.cpp` now also use the
+  instance they are invoked on instead of a global `App::I` fallback.
 - The retained Web fallback service object and the Apple storage-path
   preparation helper now also live in
   `src/platform_legacy/legacy_platform_state.*` instead of being built inline