Add Score and Stage model

app/models/score.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+class Score < ApplicationRecord
+  belongs_to :match
+  belongs_to :team
+end

app/models/stage.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class Stage < ApplicationRecord
+  belongs_to :tournament
+  has_many :matches, dependent: :destroy
+  has_many :groups, dependent: :destroy
+end