Lengthen the WHOIS fetcher's wait after a skipped lookup (closes #222)

A lookup whose RIR is paused is skipped. The skip left the fetcher's wait
as it was. Each lookup asks IANA before it finds its RIR paused. So while
most stale ASes belonged to a paused RIR, the fetcher could ask IANA every
second.

Like a failure, a skipped lookup now makes the wait 1.5 times as long, up
to one minute. The skip is still not counted as a failure, so the status
page's failure figures leave it out.

Model: opus-5-5

TODO.md

@@ -35,6 +35,12 @@ tested.
 
 # Completed Steps
 
+- 2026-11-02: like a failed WHOIS lookup, a lookup skipped because its RIR is
+  paused makes the fetcher wait longer before the next lookup. The longest wait
+  is one minute. The status page does not count a skip as a failure. A skip used
+  to leave the wait as it was. Each lookup asks IANA before it finds its RIR
+  paused. So while most stale ASes belonged to a paused RIR, the fetcher could
+  ask IANA every second (closes #222)
 - 2026-11-02: a peer's session going down no longer stops the prefix handler.
   The handler runs the table's `PeerDown` on a separate goroutine, one peer at a
   time, and goes on taking messages. `PeerDown` holds the table's lock for