Pause a WHOIS server for an hour after it refuses a query (closes #218)

The fetcher kept one interval for every registry, so a registry that
refused a query was asked again within seconds. RIPE blocked the test
host's address that way.

The WHOIS client now asks a server nothing for an hour after the server
refuses a query. A refusal is a refused or reset connection, or an
%ERROR:201: or %ERROR:202: line. The other servers are still asked. A
lookup that needs a paused server leaves the AS stale, and counts as
neither a success nor a failure. NIC.br's hour-long skip after its
over-limit answer is now the same pause.

Model: opus-5-5

TODO.md

@@ -35,6 +35,14 @@ tested.
 
 # Completed Steps
 
+- 2026-11-02: after a WHOIS server refuses a query, RouteWatch asks it nothing
+  for an hour. A refusal is a refused or reset connection, or an `%ERROR:201:`
+  or `%ERROR:202:` line, with which RIPE, APNIC and AFRINIC refuse a query.
+  RouteWatch still asks the other servers. An AS whose server is paused is
+  looked up after the pause. Every lookup asks IANA first, so a pause of IANA
+  stops them all. The fetcher used to ask a server that had refused it again
+  within seconds. NIC.br's answer that RouteWatch is over its limit starts the
+  same pause (closes #218)
 - 2026-10-27: the tests of `internal/routewatch` no longer fail on a loaded
   host. Five of them gave `HandleMessage` two seconds to apply a full prefix
   batch, which under the race detector can take longer. A test now waits up to