feat: add atomic update for single member field visibility

lib/membership/member.ex

@@ -40,6 +40,8 @@ defmodule Mv.Membership.Member do
   import Ash.Expr
   require Logger
 
+  alias Mv.Membership.Helpers.VisibilityConfig
+
   # Module constants
   @member_search_limit 10
 
@@ -607,7 +609,7 @@ defmodule Mv.Membership.Member do
       {:ok, settings} ->
         visibility_config = settings.member_field_visibility || %{}
         # Normalize map keys to atoms (JSONB may return string keys)
-        normalized_config = normalize_visibility_config(visibility_config)
+        normalized_config = VisibilityConfig.normalize(visibility_config)
 
         # Get value from normalized config, use field-specific default
         Map.get(normalized_config, field, default_visibility)
@@ -959,29 +961,6 @@ defmodule Mv.Membership.Member do
   defp error_type(error) when is_atom(error), do: error
   defp error_type(_), do: :unknown
 
-  # Normalizes visibility config map keys from strings to atoms.
-  # JSONB in PostgreSQL converts atom keys to string keys when storing.
-  defp normalize_visibility_config(config) when is_map(config) do
-    Enum.reduce(config, %{}, fn
-      {key, value}, acc when is_atom(key) ->
-        Map.put(acc, key, value)
-
-      {key, value}, acc when is_binary(key) ->
-        try do
-          atom_key = String.to_existing_atom(key)
-          Map.put(acc, atom_key, value)
-        rescue
-          ArgumentError ->
-            acc
-        end
-
-      _, acc ->
-        acc
-    end)
-  end
-
-  defp normalize_visibility_config(_), do: %{}
-
   @doc """
   Performs fuzzy search on members using PostgreSQL trigram similarity.