Add media retention cleanup command

demo/README.md

@@ -30,6 +30,20 @@ variants are written under `images/thumbs/` inside each feed output directory.
 Edit the Scrapy settings in [`demo/repub.toml`](/home/abel/src/guardianproject/anynews/republisher-redux/demo/repub.toml)
 when a demo run needs to disable thumbnails or test a different profile set.
 
+## Media Cleanup
+
+Published media can remain on disk after articles fall out of the current feed.
+Run cleanup in dry-run mode first:
+
+```shell
+uv run repub cleanup-media --config demo/repub.toml --dry-run
+```
+
+With `--config`, cleanup scans `demo/out/feeds/` and honors any
+`REPUBLISHER_*_DIR` media directory overrides in the config. Remove `--dry-run`
+to delete old unreferenced media. The default retention window is 25 days; use
+`--days N` to override it.
+
 ## Local File Feed
 
 `repub` already accepts absolute `file://` feed URIs. To point it at the demo fixture, generate an absolute URI like this from the repo root: