fix(images): background jobs skip files hidden by the removal mark; walkers skip trash folders inside output roots (#501)

- Thumbnail jobs and the legacy scan_output_dir listing leave
  library-removed files out (one mark check, mark_hides).
- Missing-file links also forgets removal marks that hide nothing any
  more (file gone from a folder that exists, or changed), only under a
  readable, non-empty source, re-checked at apply.
- The sidebar Images, Favorites and Needs review counts and the
  collection counts are read again when an image_delete job ends.
- utils/media_folders.py: one skip for thumbnails and trash folders
  (.Trash, .Trash-<uid>, .Trashes, $RECYCLE.BIN) used by every walker,
  the image monitor and the delete review.

web/js/workspace/state.mjs

@@ -129,6 +129,11 @@ export const LIBRARY_WRITE_COUNTS = Object.freeze(['library', 'tags']);
 export const FAVORITE_WRITE_COUNTS = Object.freeze(['favorites']);
 /** The count a review decision or a finished metadata scan can change. */
 export const REVIEW_WRITE_COUNTS = Object.freeze(['review']);
+/** Job kind -> the counts re-read once when such a job ends (a scan feeds Needs review; #501: a delete hides images). */
+export const JOB_END_COUNTS = Object.freeze({
+    scan: REVIEW_WRITE_COUNTS,
+    image_delete: Object.freeze(['images', 'favorites', 'review']),
+});
 // Trailing delay that coalesces quick star toggles into one Favorites count read (#249 M1).
 export const FAVORITE_COUNT_DELAY_MS = 300;