initial data model implementation

db/migrate/20260122123837_create_users.rb

@@ -0,0 +1,20 @@
+class CreateUsers < ActiveRecord::Migration[8.1]
+  def change
+    create_table :users do |t|
+      t.string :email, null: false
+      t.string :password_digest, null: false
+      t.string :name
+      t.integer :role, null: false, default: 0
+      t.string :primary_language
+      t.string :invitation_token
+      t.datetime :invitation_sent_at
+      t.datetime :invitation_accepted_at
+      t.references :invited_by, null: true, foreign_key: { to_table: :users }
+
+      t.index :email, unique: true
+      t.index :invitation_token, unique: true
+
+      t.timestamps
+    end
+  end
+end