A truncated debrid download (in-memory byte counter hit 100% while the
NFS write-back silently dropped most of the bytes) was marked completed.
The 1.1.6 fsync fix closed the debrid-specific hole; this generalizes the
guarantee so "completed" never means a corrupt file on ANY backend.
- IntegrityError + bounded retry: on a corrupt/short result the manager
re-downloads the same source up to 3x (clean start), then surfaces the
task as damaged ("corrupt download:" prefix) instead of completing it.
- verify (size mismatch / empty), debrid (incomplete / post-write / flush),
torrent (BytesMissing), usenet (par2 unrepairable / repair-failed) all
classify integrity failures so they route through the retry/damaged path.
- scanner: a file ffprobe can't read is emitted as a damaged library_item
(reason "unreadable") instead of being silently dropped from the sync.
- tests: manager retry-then-success + retry-exhausted-then-damaged,
verifying->resolving transition, damaged sync item.
- Replace `upgrade` stub with real command (alias for `self-update`)
- Also register `update` as alias: `unarr update` works too
- Rewrite `status` to show full config, disk usage, daemon state, and
update availability with colored sections
- Add version check cache (1h TTL) so `status` is instant on repeat runs
- Guard against division by zero on empty filesystems
- Guard against negative durations from clock skew
- Guard against stale PID via heartbeat recency check (2 min)
- Add comprehensive test coverage across agent, engine, upgrade, usenet,
arr, library, mediaserver, and UI packages
- Improve Makefile coverage target to exclude cmd/ glue code
- Fix stream handler resource cleanup and ffprobe error handling
