Move Apple retained platform state into platform target

docs/modernization/tasks.md

@@ -47,6 +47,10 @@ Completed, blocked, and superseded task history moved to
     reporting now uses an injected callback, but retained Apple bridging and
     broader platform-to-app singleton reach are still open in
     `platform_legacy`
+  - Apple retained bridge/state ownership now lives in
+    `src/platform_apple/apple_platform_state.cpp` and
+    `src/platform_apple/apple_platform_services.*`, but the legacy platform
+    facade still routes a broad Apple service surface instead of disappearing
   - `platform_legacy` is still part of the live app shell
 - The app runtime boundary is not finished:
   - render/UI queues are static `App` state
@@ -1205,6 +1209,15 @@ Why now:
 platform-handle state on `App`, which blocks a real `pp_platform_*` shell split.
 
 Current slice:
+- The retained Apple document bridge/state pocket no longer lives in
+  `src/platform_legacy/legacy_platform_state.*`; it now lives in the
+  Apple-owned `src/platform_apple/apple_platform_state.cpp` and
+  `src/platform_apple/apple_platform_services.*`, and the macOS/iOS
+  entrypoints now seed that state through `pp::platform::apple`.
+- `src/platform_legacy/legacy_platform_services.cpp` now consumes the
+  Apple-owned retained provider/factory through `pp::platform::apple::...`
+  call-throughs instead of constructing or caching Apple retained bridge
+  state in the legacy layer.
 - The Win32 stylus and pointer-input path no longer reaches
   `WacomTablet::I` directly in
   `src/platform_windows/windows_window_shell.cpp` or