Centralize legacy video export bridge

docs/modernization/build-inventory.md

@@ -563,7 +563,8 @@ Known local toolchain state:
   invalid export naming inputs, plus export-start license/canvas availability
   decisions, export menu executor dispatch, file/stem/collection export
   execution dispatch, failed directory creation preservation, named depth/cube
-  export dispatch, and malformed export target rejection.
+  export dispatch, malformed export target rejection, video export dispatch for
+  animation MP4/timelapse paths, and empty video-path rejection.
 - `pp_app_core_document_recording_tests` covers recording start/stop, clear,
   platform recorded-file cleanup, frame-count reset, export progress totals,
   and oversized progress-total clamping.
@@ -612,7 +613,11 @@ Known local toolchain state:
   layers, animation-frame, depth, and cube-face export calls. It preserves
   platform-specific export messages, directory creation, picker-selected stem
   exports, Web prepared-file handoff, and legacy `Canvas` export execution while
-  retained renderer/document/platform ownership is tracked by `DEBT-0043`.
+  retained renderer/document/platform ownership is tracked by `DEBT-0043`. It
+  also bridges timelapse and animation MP4 export picker-selected paths while
+  preserving desktop worker-thread timelapse behavior, mobile/Web save
+  callbacks, `App::rec_export`, animation `Canvas::export_anim_mp4`, and
+  success messages; retained video/export ownership is tracked by `DEBT-0044`.
 - `src/legacy_history_services.*` is the current app-shell bridge between
   `pp_app_core` history plans and legacy `ActionManager`; toolbar and
   `NodeCanvas` hotkeys share it while document-history extraction remains