fix(Vpc): use self.natInstances in registerOutputs to fix Vpc.get() with bastion (#6347)

When using Vpc.get() to reference an existing VPC created with bastion: true,
deployment fails with "Cannot access 'natInstances' before initialization".

The registerOutputs() function incorrectly references the local variable
`natInstances` instead of the class property `self.natInstances`. In the ref
path (Vpc.get), registerOutputs() is called before the local variable is
defined, but the class property is already set from ref.natInstances.

Fixes #6346

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: brendan-smp

platform/src/components/aws/vpc.ts

@@ -690,7 +690,7 @@ export class Vpc extends Component implements Link.Linkable {
           ([bastion, elasticIps, privateKeyValue, privateSubnets, publicSubnets]) => {
             if (!bastion) return;
             return {
-              ip: natInstances.apply((instances) =>
+              ip: self.natInstances.apply((instances) =>
                 instances.length ? elasticIps[0]?.publicIp : bastion.publicIp,
               ),
               username: "ec2-user",