Linked zones: PTR records follow each view, deleting an override stays deleted

Auto-PTR (and --ptr) changed PTR records in every linked view, whatever
view the address record was in. ptrSync now compares each touched A/AAAA
set before and after, per view, and changes only that view's reverse
zone. PTR records in linked reverse zones are local (fill too); a shared
PTR set is made local in each view before one view changes it.

Deleting a linked zone's local records no longer brings the shared ones
back into the view: the name and type are gone from that view and the
other views keep theirs, local to each. Share still restores.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/cli.md

@@ -318,7 +318,8 @@ host name (a bare `nas` is refused, since it would mean
 keeps the PTR record in the reverse zone in step (when that zone is managed
 by Jarl); `jarl record update ID --ptr` with nothing else adds the PTR record
 if it is missing, e.g. after creating the reverse zone. In linked zones, the
-reverse zones of every linked view count. Every record type BIND supports can be used. Jarl knows the
+reverse zone of each linked view that has the record counts
+([reverse.md](reverse.md#keeping-ptr-records-in-step)). Every record type BIND supports can be used. Jarl knows the
 syntax of the common ones and checks them strictly, and the rest are
 validated by parsing.