feat: add phone validation

lib/membership/phone_number.ex

@@ -0,0 +1,28 @@
+defmodule Mv.Membership.PhoneNumber do
+  @match_pattern ~S/^\+?\d{5,16}$/
+  @match_regex Regex.compile!(@match_pattern)
+
+  use Ash.Type.NewType,
+    subtype_of: :string,
+    constraints: [
+      match: @match_pattern,
+      trim?: true
+    ]
+
+  @impl true
+  def cast_input("", _), do: {:ok, nil}
+
+  @impl true
+  def cast_input(value, _) when is_binary(value) do
+    value = String.trim(value)
+
+    if Regex.match?(@match_regex, value) do
+      {:ok, value}
+    else
+      :error
+    end
+  end
+
+  @impl true
+  def cast_input(_, _), do: :error
+end