`ash_postgres.generate_migrations` not `dumping_to_native` when generating a default value

[adamtharani]

Describe the bug When using a custom type for an attribute with a default value the migration is generated with the internal value rather than the dump_to_native value

To Reproduce A minimal set of resource definitions and calls that can reproduce the bug.

Expected behavior The generated migration to have the default value as the one that gets returned from dump_to_native

** Runtime

• elixir 1.18.1-otp-27
• erlang 27.1.3
• macOS 15.5
• Ash 3.4.68
• Ash Postgres 2.5.11

Additional context Add any other context about the problem here.