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/reverse.md

@@ -147,9 +147,24 @@ jarl zone update adbraun.lol --view internal --auto-ptr          # off: --auto-p
 
 (Zone settings → **Reverse DNS** in the web UI.) Then adding, changing,
 disabling, enabling or deleting an A or AAAA record in the zone does the
-same to its PTR record, in the reverse zones of the zone's view and of the
-views it is linked with ([views.md](views.md#linked-zones)). A whole set
-replaced at once (`jarl record set`, a batch) works too.
+same to its PTR record, in the reverse zone of each view that has the
+record. A whole set replaced at once (`jarl record set`, a batch) works
+too.
+
+**Linked zones** ([views.md](views.md#linked-zones)). PTR records follow
+each view's own address records:
+
+* A shared record gets a PTR record in every linked view that has it; a
+  record local to one view gets one in that view only.
+* An address that goes from one view (deleted, changed, or overridden by
+  a local record) loses its PTR record there only. Views that still have
+  the address keep theirs.
+* Each zone's own **Reverse DNS** setting counts: a linked zone without
+  it doesn't get PTR records from its partner's changes.
+* In a linked reverse zone, these PTR records (and those **Fill** adds)
+  are local to their view. A PTR record that is shared becomes local in
+  each view the first time one of them changes it, so that a change in
+  one view doesn't reach the others.
 
 * **One name per address.** When an address's PTR record names another
   host, it stays: a second A record for the same address doesn't add a