add some comments

priv/repo/migrations/20250926164519_member_relation.exs

@@ -8,6 +8,8 @@ defmodule Mv.Repo.Migrations.MemberRelation do
   use Ecto.Migration
 
   def up do
+    # Ensure 1:1 relationship - one user can only be linked to one member
+    # This prevents multiple users from sharing the same member account
     create unique_index(:users, [:member_id], name: "users_unique_member_index")
   end
 

priv/repo/migrations/20250926180341_add_unique_email_to_members.exs

@@ -8,6 +8,8 @@ defmodule Mv.Repo.Migrations.AddUniqueEmailToMembers do
   use Ecto.Migration
 
   def up do
+    # Ensure email uniqueness across all members
+    # This supports upsert operations and prevents duplicate member accounts
     create unique_index(:members, [:email], name: "members_unique_email_index")
   end