Move project save target planning to app core

docs/modernization/build-inventory.md

@@ -297,6 +297,12 @@ powershell -ExecutionPolicy Bypass -File scripts\automation\apple-remote-build.p
   1024x1024 draw/readback plan counts. It is covered by
   `pano_cli_plan_canvas_document_snapshot_smoke` plus the payload-bearing
   snapshot smoke.
+- `pano_cli plan-canvas-project-save-target` exposes the app-core planner for
+  retained project-save target paths, including the requested PPI path,
+  temporary `.tmp.ppi` path, and timelapse `.pptl` sidecar path. The live
+  `Canvas::project_save_thread` consumes the same planner before retained
+  serialization, and the command is covered by forward-slash, Windows
+  backslash, and invalid-path smokes.
 - Live equirectangular, layer, animation-frame, and cube-face export adapters
   now prepare and log the same payload-bearing canvas document snapshot plus
   shared paint-renderer export-readiness report.
@@ -1174,8 +1180,9 @@ powershell -ExecutionPolicy Bypass -File scripts\automation\apple-remote-build.p
   overwrite prompts, document field updates, title updates, and keyboard/dialog
   cleanup. Existing Save, Save As, Save Version, and save-before-workflow
   prepare and log a payload-bearing canvas document snapshot report, run the
-  app-core pure PPI save-writer route for payload-complete snapshots, and log
-  generated byte counts before delegating to retained `Canvas::project_save`.
+  app-core pure PPI save-writer route for payload-complete snapshots, log
+  generated byte counts, and derive project-save target/tmp/timelapse paths
+  through `pp_app_core` before delegating to retained `Canvas::project_save`.
   Retained legacy UI/canvas
   execution and actual live save serialization remain tracked by `DEBT-0040`,
   `DEBT-0041`, and `DEBT-0042`; the pure snapshot-to-PPI export handoff is