feat: implement popping nms

app/models/instance.rb

@@ -1,3 +1,5 @@
 class Instance < ApplicationRecord
+  has_many :pops
+
   validates :zone, inclusion: { in: %w[anemos pagos pyros hydatos] }
 end

app/models/pop.rb

@@ -0,0 +1,3 @@
+class Pop < ApplicationRecord
+  belongs_to :instance
+end