chore: refactoring of Repo.get/get! usages

lib/bds/ai/chat.ex

@@ -53,6 +53,11 @@ defmodule BDS.AI.Chat do
     |> Enum.map(&format_conversation/1)
   end
 
+  @spec get_chat_conversation(String.t()) :: ChatConversation.t() | nil
+  def get_chat_conversation(conversation_id) when is_binary(conversation_id) do
+    Repo.get(ChatConversation, conversation_id)
+  end
+
   @spec available_chat_models(String.t() | nil) :: [map()]
   def available_chat_models(current_model \\ nil) do
     endpoint_models = configured_chat_models()

lib/bds/ai/chat_conversation.ex

@@ -6,6 +6,15 @@ defmodule BDS.AI.ChatConversation do
 
   @primary_key {:id, :string, autogenerate: false}
 
+  @type t :: %__MODULE__{
+          id: String.t(),
+          title: String.t() | nil,
+          model: String.t() | nil,
+          copilot_session_id: String.t() | nil,
+          created_at: integer() | nil,
+          updated_at: integer() | nil
+        }
+
   schema "chat_conversations" do
     field :title, :string
     field :model, :string