feat(infra): PR #7 — Terraform ECS compute + autoscaling

[devin-ai-integration]

Summary

Wave 2 / PR #7. Self-contained Terraform root infra/compute/ running the GnuCOBOL batch/service containers on ECS Fargate with health checks and target-tracking autoscaling. Consumes infra/network (subnets, SG) and infra/storage (EFS id/access point) outputs via variables; parameterized by var.programs so onboarding a service is config-only.

infra/compute/
  main.tf         # ecs_cluster; per-program task_definition (EFS volume -> data_root,
                  #   container healthCheck -> /health sidecar, awslogs) + ecs_service (Fargate, circuit breaker)
  iam.tf          # execution role (ECR pull + logs) and task role (EFS ClientMount/Write)
  autoscaling.tf  # appautoscaling_target + CPU target tracking (always);
                  #   optional SQS queue-depth (backlog/task) when scale_on_queue_depth=true
  variables.tf outputs.tf versions.tf

Key points hard to see from the diff:

• Health check uses python3 urllib (already in the image — no curl needed) so ECS marks a task unhealthy when /health returns 503, which the entrypoint sets on program failure.
• Task runs with MODE=service so the container stays up for the service/autoscaling model (vs oneshot batch).
• local.images falls back to a placeholder ECR URL when ecr_repository_urls is empty, so the root plans/validates offline before Add User ID alphanumeric validation for MBA-123 #5 outputs are wired.

Verified locally

• terraform fmt, terraform init -backend=false, terraform validate → Success! The configuration is valid.

Links

• docs/modernization/CURRENT_STATE_ANALYSIS.md §6 (no autoscaling/health today)
• Consumes PR Add User ID alphanumeric validation for MBA-123 #5 (network/ECR) + PR Migrate Card Numbers from Numeric to Alphanumeric #6 (EFS) outputs.

Link to Devin session: https://app.devin.ai/sessions/c0f261ce337a4aee965332f1754d037a
Requested by: @vibhaseshadri-cognition

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