download_layout and download_retention_days are registered ConfigSpec keys
(admin-editable on the Configuration page), but worker.py read them from
settings.* (env) at download/edit finalize time — so an admin's edit was a
silent no-op (files kept the old layout; TTL stayed at the env default). Read
them via sysconfig (_download_settings), which falls back to the env default
when there's no DB override. Same class as the Downloads B3 fix.
ruff clean, localdev boots, re-review clean.
peter
7e18d9698f