create basic backend with login

main-server/db/migrate/20260920183453_create_sessions.rb

@@ -0,0 +1,11 @@
+class CreateSessions < ActiveRecord::Migration[8.1]
+  def change
+    create_table :sessions do |t|
+      t.references :user, null: false, foreign_key: true
+      t.string :ip_address
+      t.string :user_agent
+
+      t.timestamps
+    end
+  end
+end