fix: v0.6.2 — structural tracker refactor, batch writes, multi-instance prep

- Drop flat list as primary storage; derive uploaded/rejected IDs from by_person
  (single source of truth). Legacy flat lists in existing files still read for
  backward compat. Removes dual-representation sync hazard.
- Add begin_batch/flush_batch: per-person upload loop now does 1 os.replace
  instead of N (one per mark_uploaded call). Benefit on slow storage.
- reset_all_people(): RESET_PERSON=* is now O(1) disk writes instead of O(P^2).
- blur_score_from_image inlines cv2.Laplacian directly, removing assess_quality
  call overhead and decoupling from the full quality pipeline.

uv.lock

@@ -862,7 +862,7 @@ wheels = [
 
 [[package]]
 name = "winnow"
-version = "0.6.0"
+version = "0.6.1"
 source = { editable = "." }
 dependencies = [
     { name = "croniter" },