bingo: add, delete and reorder datacenters from admin

The card was fixed to the 25 seeded rows, so a new site such as
IXcellerate MOS7 (34 MW, under construction) could only be shoehorned in
by overwriting an existing row. Add create and delete (cascading to
incidents), make position an insert that shifts the rest, and keep
positions dense. More than 25 rows are allowed: the card shows the first
25 and the rest wait in reserve. "Sort by MW" re-ranks by the parsed
power figure, unknown last.

Assisted-by: Claude:opus-5

lib/bingo.rb

@@ -238,6 +238,34 @@ module Bingo
     end
   end
 
+  # Positions stay dense 1..N; the card shows the first SIZE*SIZE, the rest
+  # wait in reserve. Placing a datacenter inserts it at pos (default: last)
+  # and shifts everyone after it.
+  def self.place!(dc, pos = nil)
+    DB.connection.transaction do
+      ids = Datacenter.exclude(id: dc.id).order(:position, :id).select_map(:id)
+      pos = (pos || ids.size + 1).clamp(1, ids.size + 1)
+      renumber!(ids.insert(pos - 1, dc.id))
+    end
+  end
+
+  def self.renumber!(ids = Datacenter.order(:position, :id).select_map(:id))
+    ids.each_with_index { |id, i| Datacenter.where(id: id).update(position: i + 1) }
+  end
+
+  # "64" → 64.0, "25–30" → 30.0, ">40" → 40.0, "13,7" → 13.7, "" → nil
+  def self.mw_value(mw)
+    mw.to_s.tr(',', '.').scan(/\d+(?:\.\d+)?/).map(&:to_f).max
+  end
+
+  # Rank by power, unknown last; ties keep their current order.
+  def self.sort_by_mw!
+    DB.connection.transaction do
+      renumber!(Datacenter.order(:position, :id).all
+                          .sort_by.with_index { |dc, i| [-(mw_value(dc.mw) || -1), i] }.map(&:id))
+    end
+  end
+
   # First boot: fill the card (and any already-known incidents) from
   # db/bingo_seed.json. Never touches rows once any exist; edits happen in
   # /admin/bingo.