Added Ecto, Cassandra and Auctions repo

priv/repo/migrations/20260715174940_add_auctions_table.exs

@@ -0,0 +1,11 @@
+defmodule NeonVertigoService.Repo.Migrations.AddAuctionsTable do
+  use Ecto.Migration
+
+  def change do
+    create table("auctions", primary_key: false) do
+      add :gid, :string, primary_key: true
+      add :author_gid, :string, null: false
+      add :starting_price, :decimal, null: false
+    end
+  end
+end