feat: custom field deletion

lib/membership/custom_field_value.ex

@@ -25,11 +25,12 @@ defmodule Mv.Membership.CustomFieldValue do
 
   ## Relationships
   - `belongs_to :member` - The member this custom field value belongs to (CASCADE delete)
-  - `belongs_to :custom_field` - The custom field definition
+  - `belongs_to :custom_field` - The custom field definition (CASCADE delete)
 
   ## Constraints
   - Each member can have only one custom field value per custom field (unique composite index)
   - Custom field values are deleted when the associated member is deleted (CASCADE)
+  - Custom field values are deleted when the associated custom field is deleted (CASCADE)
   - String values maximum length: 10,000 characters
   - Email values maximum length: 254 characters (RFC 5321)
 
@@ -46,12 +47,19 @@ defmodule Mv.Membership.CustomFieldValue do
 
     references do
       reference :member, on_delete: :delete
+      reference :custom_field, on_delete: :delete
     end
   end
 
   actions do
     defaults [:create, :read, :update, :destroy]
     default_accept [:value, :member_id, :custom_field_id]
+
+    read :by_custom_field_id do
+      argument :custom_field_id, :uuid, allow_nil?: false
+
+      filter expr(custom_field_id == ^arg(:custom_field_id))
+    end
   end
 
   attributes do