feat: more completeness of spec and start at embedding

lib/bds/embeddings/key.ex

@@ -0,0 +1,25 @@
+defmodule BDS.Embeddings.Key do
+  @moduledoc false
+
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key {:label, :integer, autogenerate: false}
+  @foreign_key_type :string
+
+  schema "embedding_keys" do
+    belongs_to :post, BDS.Posts.Post, type: :string
+    belongs_to :project, BDS.Projects.Project, type: :string
+
+    field :content_hash, :string
+    field :vector, :string
+  end
+
+  def changeset(key, attrs) do
+    key
+    |> cast(attrs, [:label, :post_id, :project_id, :content_hash, :vector])
+    |> validate_required([:label, :post_id, :project_id, :content_hash, :vector])
+    |> foreign_key_constraint(:post_id)
+    |> foreign_key_constraint(:project_id)
+  end
+end