The cleanup-tags.sh + garbage-collect cycle can delete blob data while
leaving _layers/ link files intact. The registry then returns HTTP 200
with 0 bytes for those layers, causing "unexpected EOF" on image pulls.
fix-broken-blobs.sh walks all repositories, checks each layer link
against actual blob data, and removes orphaned links so the registry
re-fetches from upstream on next pull.
Schedule: daily at 2:30am (after tag cleanup) and Sunday 3:30am
(after garbage collection). First run found 2335/2556 (91%) of
layer links were orphaned.
