fix: persist a2ui surfaces in the database for chats to re-hydrate on

opening an old chat, unless manually dismissed

lib/bds/ai/chat_conversation.ex

@@ -11,6 +11,7 @@ defmodule BDS.AI.ChatConversation do
           title: String.t() | nil,
           model: String.t() | nil,
           copilot_session_id: String.t() | nil,
+          surface_state: map() | nil,
           created_at: integer() | nil,
           updated_at: integer() | nil
         }
@@ -19,13 +20,14 @@ defmodule BDS.AI.ChatConversation do
     field :title, :string
     field :model, :string
     field :copilot_session_id, :string
+    field :surface_state, :map
     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],
+    |> cast(attrs, [:id, :title, :model, :copilot_session_id, :surface_state, :created_at, :updated_at],
       empty_values: [nil]
     )
     |> validate_required([:id, :title, :created_at, :updated_at])