グカネータ作成 (#041) (#362)

Reviewed-on: #362
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

backend/db/migrate/20260610000000_create_gekanator_question_examples.rb

@@ -0,0 +1,19 @@
+class CreateGekanatorQuestionExamples < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_question_examples do |t|
+      t.references :gekanator_question, null: false, foreign_key: true
+      t.references :post, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+      t.references :gekanator_game, null: true, foreign_key: true
+      t.string :answer, null: false
+      t.string :source, null: false, default: 'post_game_extra'
+      t.float :weight, null: false, default: 1.0
+      t.timestamps
+    end
+
+    add_index :gekanator_question_examples,
+              [:gekanator_question_id, :post_id, :user_id],
+              unique: true,
+              name: 'idx_gekanator_question_examples_on_question_post_user'
+  end
+end