SimpleCheck for field-level authorization within Ash's field_policies.

This check integrates with Ash's built-in field_policies system to authorize access to specific fields based on AshGrant permission strings.

Usage (Mode A — Manual)

field_policies do
  field_policy [:salary, :ssn] do
    authorize_if AshGrant.field_check(:confidential)
  end

  field_policy [:phone, :address] do
    authorize_if AshGrant.field_check(:sensitive)
  end

  field_policy :* do
    authorize_if always()
  end
end

The check passes if the actor's permission string has a field_group that equals or inherits from the required group. If the actor's permissions have no field_group (4-part format), all fields are visible.