add lead job invitations migration

Creates table to track job invitation statuses between users and lead jobs.

Author: zcesur

priv/repo/migrations/20250608181029_create_lead_job_invitations.exs

@@ -0,0 +1,19 @@
+defmodule Algora.Repo.Migrations.CreateLeadJobInvitations do
+  use Ecto.Migration
+
+  def change do
+    create table(:lead_job_invitations, primary_key: false) do
+      add :id, :string, primary_key: true
+      add :status, :string, null: false, default: "pending"
+
+      add :user_id, references(:users, type: :string, on_delete: :delete_all), null: false
+      add :lead_job_id, references(:lead_jobs, type: :string, on_delete: :delete_all), null: false
+
+      timestamps()
+    end
+
+    create unique_index(:lead_job_invitations, [:user_id, :lead_job_id],
+             name: :lead_job_invitations_user_id_lead_job_id_index
+           )
+  end
+end