Free validator ports in the cloud on clear/cancel/delete

An address still being associated (assigning_fip) has no fip_id in the
database, so "clear queue" did not detach it, and the association then
finished after the row was gone, leaving the floating IP on the validator
port for good.

- After clear/cancel/delete, ask the cloud which floating IPs sit on the
  affected validator ports (new ListFloatingIPsByPort) and detach those
  that this system queued (known in ip_registry); foreign ones are left.
- SetFIPAssociated applies only to a row still in assigning_fip; if the
  address was removed meanwhile, associateFIP detaches the floating IP.

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

bin/SHA256SUMS

@@ -1,4 +1,4 @@
-4562d3cf3db8075b5a1213b582359991e3f58c819151cf7b25276cba0a4e5985  control-api
+4302c5d936b0f6567e4b3b7af3de0123afd862b3cdda53859fad0c7eec443c33  control-api
 091ad94b5706b1778b181542de7a4b251cd16c421144269d0955769603d51e06  validator-agent
 3e9e14dbb361ee76aaad7c1da6864b3ea111e0ed151403f904b12485631bbf75  prober
 d72234688eb1954dbff420ca1c8e83b83ceab561b18a0336af0f73fe4d9ac8be  admin-dashboard