Plan cube export face targets in app core

docs/modernization/roadmap.md

@@ -529,7 +529,8 @@ candidate generation, collision skipping, and no-slot failure behavior used by
 the live save-version dialog.
 `pano_cli plan-export-target` exposes app-core export target planning for
 equirectangular image files, layer/frame collection stems, picked-directory
-stems, and MP4 suggested names used by the live export dialogs.
+stems, cube-face work-directory file sets, and MP4 suggested names used by the
+live export dialogs and cube-face writer bridge.
 `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
 plus MP4 animation and timelapse export dialogs before they call legacy
@@ -688,10 +689,10 @@ renderer-owned readback remain under
 Live equirectangular, layer, animation-frame, and cube-face export adapters now
 prepare the same payload-bearing document snapshot and renderer-neutral upload
 report helper plus pure face-PNG export report. Cube-face export writes those
-document/renderer-owned PNG bytes to the legacy face filenames when available
-and falls back to retained `Canvas::export_cube_faces` on snapshot/write failure;
-the other export workflows still delegate to retained `Canvas` writers after
-readiness reporting.
+document/renderer-owned PNG bytes to the app-core-planned legacy face filenames
+when available and falls back to retained `Canvas::export_cube_faces` on
+snapshot/write failure; the other export workflows still delegate to retained
+`Canvas` writers after readiness reporting.
 `pano_cli plan-image-import` exposes app-core planning for File > Import image
 route decisions, including wide equirectangular images, legacy vertical cube
 strips, regular transform-placement images, and invalid image dimensions; live
@@ -2531,10 +2532,10 @@ Results:
 - Live image/collection/cube export adapters now prepare and log the same
   document/canvas plus shared renderer-upload and face-PNG export readiness
   reports. Cube-face export now writes the pure document/renderer PNG bytes to
-  the legacy face filenames before falling back to retained `Canvas` execution
-  on failure. Equirectangular, layer, animation-frame, depth, and video export
-  remain on their prior retained writer paths; actual broader writer replacement
-  remains tracked under export debt.
+  the `pp_app_core` planned legacy face filenames before falling back to
+  retained `Canvas` execution on failure. Equirectangular, layer,
+  animation-frame, depth, and video export remain on their prior retained writer
+  paths; actual broader writer replacement remains tracked under export debt.
 - Snapshot creation now rejects invalid embedded RGBA8 face payloads before
   document export or history can persist malformed state.
 - Package-smoke wrappers validate the Windows CMake app executable/runtime