Defensive field-reading helpers for post-action notifier hooks.

Why this exists

Ash actions can use narrowed select clauses to return only a subset of attributes. The excluded attributes are populated as %Ash.NotLoaded{} sentinels rather than raising or returning nil.

Notifier hooks (counter broadcasts, locale extraction, dispatch context building) read fields off the action's resulting record to decide what to do next. A bare Map.get(record, field) returns the sentinel for narrowed fields, which then cascades into:

• Ecto.Query.CastError when used in a query filter
• ArgumentError "Actor field is not loaded" from Ash.Query.relates_to_actor_via checks
• Protocol.UndefinedError{protocol: String.Chars} when interpolated into a topic string or log message
• Truthy-check bugs: if Map.get(record, :foo) is true for a sentinel because it's a struct, not nil/false

The contract

Notifier side effects are best-effort — they must degrade silently when the record can't yield the field, not crash the request or spam the log. These helpers treat %Ash.NotLoaded{} as nil so callers' existing nil-checks make the right decision automatically.

Single debug log per call so production diagnostics are still available without polluting test output.