DNSSEC: say where the DS record really goes

The DNSSEC tab said "give this to your registrar" for every zone whose
parent wasn't in Jarl in the same view. The DNSSEC response now has
ds_at/ds_place/ds_note: the parent zone in Jarl (any view, its own
first, then a public one), the registrar for a registered domain, the
parent zone wherever it is hosted for a subdomain, the ISP or RIR for a
reverse zone, and nowhere for a private name. The page and the CLI use
them.

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

CHANGELOG.md

@@ -33,6 +33,15 @@ All notable changes to Jarl are documented here. The format follows
 
 ### Fixed
 
+- The DNSSEC tab told you to give the DS record to your registrar for
+  every zone whose parent isn't in Jarl in the same view. Now it (and
+  `jarl zone dnssec status`, and the API's new `ds_at`, `ds_place` and
+  `ds_note`) says where it really goes: the parent zone in Jarl (in any
+  view now, the zone's own first), the registrar for a registered
+  domain, the parent zone wherever it is hosted for a subdomain, your
+  ISP or RIR for a reverse zone, and nowhere for a private name such as
+  `home.lan` (signing it has no effect).
+
 - The Registrar tab (and `jarl zone registrar`, and the DNSSEC page's
   registrar button) was offered for every zone when `porkbun.domains` is
   empty, and always failed for subdomain zones (`lab.adbraun.lol`),