docs: note the delete-region crop-cleanup gap found during magazine QA

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

TODO.md

@@ -656,3 +656,13 @@ became behaviour ("peers through small windows, moves nimbly on spiral staircase
 rather than appearance, where the older sheet had "shoulder-length white hair, faded scar
 across forehead". Prefer the app's own Character Sheets flow over evidence-window
 shortcuts when appearance quality matters.
+
+- [ ] **Magazine: deleting a picture/chart/table region leaves its crop file and article
+  reference behind.** Found 2026-09-22 while cleaning up two invented figure regions by
+  hand. `delete_region()`/`DELETE .../regions/{block_id}` matches only the block's own id;
+  a picture/chart/table's derived crop has a *different* id (`p{page}-region-{block_id}`,
+  from `crop_visual_regions`), so deleting the block leaves that crop file on disk and its
+  id in any article's `images` list (the article would still try to show a picture of
+  content that's no longer recognised as one). Fix: when the deleted id is a block with a
+  crop derived from it, also remove the `p{page}-region-{id}` image entry, delete its file,
+  and strip that derived id (not just the block id) from every article's `images` list.