docs(audiobookshelf): one page for the endpoint, and the rescan law at the relayout

The page owns the shape, the first-run account step (ABS accepts the initial
account only from a local-network address) and the laws: why the array bind is
read-only and what the one-line rollback is if on-disk sidecars are ever wanted;
why the metadata view is not that rollback; why the mount gate, the wget health
check and the amd64 digest pin are each mandatory; and that LAN-only is a posture,
not an accident.

Media Audiobook Relayout gains the third reader: ABS stores absolute paths, so the
relayout procedure has to reach its library too or it keeps rows for folders that
are gone. The vault index is regenerated, not hand-carved.

serverAppConfigs-docs/index.md

@@ -44,6 +44,7 @@ is a locator: one row, one clause, no numbers.
 
 | Page | Owns |
 |---|---|
+| [[Audiobookshelf]] | Audiobookshelf on Dankserver: quadlet shape, the read-only array bind, state on the SSD, first-run account, laws. |
 | [[Calibre]] | Calibre is the e-book library manager that backs Calibre-Web. |
 | [[Calibre-Web]] | Calibre-Web is a web application that browses, reads, and downloads eBooks from an existing Calibre library database. |
 | [[Copyparty]] | Copyparty is a lightweight file server and media streamer that runs as a single Python binary. |