Route video export start through app core

docs/modernization/build-inventory.md

@@ -416,8 +416,8 @@ Known local toolchain state:
 - `pano_cli plan-export-start` exposes `pp_app_core` export availability
   planning for license-gated, demo-blocked, and missing-canvas states as JSON;
   the live image, layer, animation-frame, depth, and cube-face export dialogs
-  consume the same start contract before reaching legacy canvas export
-  execution.
+  plus MP4 animation and timelapse export dialogs consume the same start
+  contract before reaching legacy canvas/recording export execution.
 - `pano_cli simulate-app-session` exposes `pp_app_core` project-open,
   app-close, save, save-as, save-version, and save-before-workflow decisions
   as JSON and is covered for clean, dirty, already-prompting, missing-canvas,

docs/modernization/roadmap.md

@@ -442,7 +442,8 @@ equirectangular image files, layer/frame collection stems, picked-directory
 stems, and MP4 suggested names used by the live export dialogs.
 `pano_cli plan-export-start` exposes the app-core export availability decision
 used by live image, layer, animation-frame, depth, and cube-face export dialogs
-before they call legacy canvas export execution.
+plus MP4 animation and timelapse export dialogs before they call legacy
+canvas/recording export execution.
 `pano_cli parse-layout` exercises the XML layout path. Continue expanding
 document behavior toward legacy Canvas parity and then port OpenGL classes
 behind the renderer boundary.

src/app_dialogs.cpp

@@ -680,6 +680,9 @@ void App::dialog_ppbr_export()
 
 void App::dialog_timelapse_export()
 {
+    if (!can_start_document_export(*this, false))
+        return;
+
 #if __IOS__ || __WEB__
     const auto target = pp::app::make_document_export_suggested_name(doc_name, "-timelapse");
     if (!target) {
@@ -708,6 +711,9 @@ void App::dialog_timelapse_export()
 
 void App::dialog_export_mp4()
 {
+    if (!can_start_document_export(*this, false))
+        return;
+
 #if __IOS__ || __WEB__
     const auto target = pp::app::make_document_export_suggested_name(doc_name, "-animation");
     if (!target) {