Stream the delegation check's queries too

Every DNS query the name server checks send is now reported from
exchangeHostPort as a dig command line with a short answer (addresses,
referral, DS, NXDOMAIN) and its round-trip time; the serials check's SOA
queries keep their own events with the server's result. The delegation
check streams with ?stream=1 like /serials, and the Name servers tab
shows its queries as they happen, keeps its result and follows a running
check when you come back.

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

CHANGELOG.md

@@ -113,6 +113,13 @@ All notable changes to Jarl are documented here. The format follows
   again" asks anew. A check keeps running if you leave the tab. Behind it,
   `GET /zones/{zone}/serials?stream=1` streams the queries as
   newline-delimited JSON (docs/api.md).
+- The delegation check streams its queries the same way, every one of
+  them: finding the parent zone, its servers' addresses, the NS and DS
+  queries to each parent server and the SOA from each delegated server.
+  Each shows a short answer ("referral to katelyn.ns.cloudflare.com., …",
+  "DS 2371", "NXDOMAIN"). The serials check now lists its address lookups
+  as separate A and AAAA queries. `GET /zones/{zone}/delegation?stream=1`
+  streams them.
 - Switching a zone's tabs (Records, Settings, …) no longer blanks the page
   while the tab loads: the page changes once the tab is ready, and
   "Loading…" appears only if a page takes a while.