feat: Improve handling of association name config

lib/mv/config.ex

@@ -143,6 +143,27 @@ defmodule Mv.Config do
     |> parse_and_validate_integer(default)
   end
 
+  # ---------------------------------------------------------------------------
+  # Association name
+  # ENV variable takes priority; fallback to Settings from database.
+  # ---------------------------------------------------------------------------
+
+  @doc """
+  Returns the association name.
+
+  Reads from `ASSOCIATION_NAME` env first, then from Settings.
+  """
+  @spec association_name() :: String.t() | nil
+  def association_name do
+    env_or_setting("ASSOCIATION_NAME", :club_name)
+  end
+
+  @doc """
+  Returns true if ASSOCIATION_NAME is set (field is read-only in Settings).
+  """
+  @spec association_name_env_set?() :: boolean()
+  def association_name_env_set?, do: env_set?("ASSOCIATION_NAME")
+
   # ---------------------------------------------------------------------------
   # Vereinfacht accounting software integration
   # ENV variables take priority; fallback to Settings from database.