Scaffold out User (#20)

Reviewed-on: #20

db/migrate/20240727022931_create_users.rb

@@ -0,0 +1,11 @@
+class CreateUsers < ActiveRecord::Migration[8.0]
+  def change
+    create_table :users do |t|
+      t.string :email
+      t.string :password_digest
+
+      t.timestamps
+    end
+    add_index :users, :email, unique: true
+  end
+end