feat: 上位タグ（#64） (#173)

#64 おそらく完成

Merge remote-tracking branch 'origin/main' into feature/064

#64 バックエンドぼちぼち

Co-authored-by: miteruzo <miteruzo@naver.com>
Reviewed-on: #173

backend/db/migrate/20251009222200_create_tag_implications.rb

@@ -0,0 +1,9 @@
+class CreateTagImplications < ActiveRecord::Migration[8.0]
+  def change
+    create_table :tag_implications do |t|
+      t.references :tag, null: false, foreign_key: { to_table: :tags }
+      t.references :parent_tag, null: false, foreign_key: { to_table: :tags }
+      t.timestamps
+    end
+  end
+end

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_11_26_231500) do
+ActiveRecord::Schema[8.0].define(version: 2025_10_09_222200) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false