feat: more work on backend content and generation

lib/bds/generation/generated_file_hash.ex

@@ -0,0 +1,23 @@
+defmodule BDS.Generation.GeneratedFileHash do
+  @moduledoc false
+
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key false
+  @foreign_key_type :string
+
+  schema "generated_file_hashes" do
+    field :project_id, :string
+    field :relative_path, :string
+    field :content_hash, :string
+    field :updated_at, :integer
+  end
+
+  def changeset(record, attrs) do
+    record
+    |> cast(attrs, [:project_id, :relative_path, :content_hash, :updated_at], empty_values: [nil])
+    |> validate_required([:project_id, :relative_path, :content_hash, :updated_at])
+    |> unique_constraint(:relative_path, name: :generated_file_hashes_project_path_idx)
+  end
+end