fix: address code review points for cycle regeneration

1. Fix critical notifications bug
2. Fix today inconsistency
3. Add advisory lock around deletion
4. Improve helper function documentation
5. Improve error message UX

lib/membership_fees/changes/validate_same_interval.ex

@@ -116,7 +116,10 @@ defmodule Mv.MembershipFees.Changes.ValidateSameInterval do
 
   # Add validation error when types cannot be loaded
   defp add_type_validation_error(changeset, _reason) do
-    message = "Could not validate membership fee type intervals: type not found"
+    message =
+      "Could not validate membership fee type intervals. " <>
+        "The current or new membership fee type no longer exists. " <>
+        "This may indicate a data consistency issue."
 
     Ash.Changeset.add_error(
       changeset,