Prepare EC2 platform for repeatable releases

[ali509]

Summary

• correct EC2 launch-template instance tag placement
• make CodeDeploy draining compatible with Auto Scaling health checks
• add the ALB-to-backend and frontend HTTP network paths required by the application
• grant the GitHub OIDC role scoped S3 artifact and CodeDeploy release permissions
• document platform deployment and verification steps

Validation

• CloudFormation templates passed cfn-lint
• security guard rules passed
• CloudFormation YAML parsed successfully
• whitespace validation passed