Second page of the admin tree. Documents the four-card stats grid with
what each number actually counts (instance-wide totals; Books = every
media item including podcast episodes), the File Watcher card's data
source (/api/scanner/watch/status, armed by Auto-Scan) and its
zero-libraries meaning, Force Rescan All Libraries with its real
mechanics (one job per library, skip-on-active, backfill tool vs.
routine shallow refresh), and the Scanning panel's live progress +
Cancel all scans. Links only to pages that exist (scanning.md); the
Settings reference stays prose until that page lands.
The real-tree nav test's Administration assertion loosens further: guide
leads, everything else strictly follows usabilityOrder — durable across
the remaining page landings. Also fixes the amend this commit replaces:
its first version briefly carried a forward link to the unwritten
settings.md (caught by the link gate, now removed) — the gate worked;
the && chain around go test let the bad commit through, which is exactly
why this amend exists.
