Add EFS MountTargets (two subnets), an ALB Target Group for Forgejo (port 3000, health
checks), and a Listener Rule for host git.n-daisuke897.com; export the TargetGroup ARN. No
application-level configuration changes.
Introduce dedicated CloudFormation templates for Forgejo networking
(EFS mount targets, ALB target group and listener rule) and S3 storage,
including bucket creation and scoped access policy.