feat: start on AI integration

lib/bds/ai/chat_conversation.ex

@@ -0,0 +1,22 @@
+defmodule BDS.AI.ChatConversation do
+  @moduledoc false
+
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key {:id, :string, autogenerate: false}
+
+  schema "chat_conversations" do
+    field :title, :string
+    field :model, :string
+    field :copilot_session_id, :string
+    field :created_at, :integer
+    field :updated_at, :integer
+  end
+
+  def changeset(conversation, attrs) do
+    conversation
+    |> cast(attrs, [:id, :title, :model, :copilot_session_id, :created_at, :updated_at], empty_values: [nil])
+    |> validate_required([:id, :title, :created_at, :updated_at])
+  end
+end