bingo: add a reachability monitor for the status page

datacenterbingo gets a public page showing whether each datacenter's
network answers. The probing lives here, next to the schema and the
admin, since the public site only has a read-only role.

bin/monitor runs as a second container from the same image. Once a
minute it opens one TCP connection to every active target (a handshake
or a refusal both count as answered) and folds the results into
5-minute rows per datacenter, plus a per-bucket row for control hosts in
Russia, so a lost vantage point isn't mistaken for dark sites. Rows are
kept 30 days. Targets are managed at /admin/bingo/monitor; only hosts a
public source ties to that one site belong there.

Migration 017 also grants the new tables to the bingo role, so the
public site can read them without a storage redeploy.

Assisted-by: Claude:opus-5-5

asxpio.rb

@@ -38,6 +38,7 @@ if ENV['DATABASE_URL']
   require_relative 'lib/invoice_pdf'
   require_relative 'lib/invoice_stats'
   require_relative 'lib/bingo'
+  require_relative 'lib/bingo_monitor'
   Bingo.seed!
   require_relative 'lib/user'
   require_relative 'lib/audit'