feat(P4): Nova rebrand — AWS resource migration (REQ-163)

Rename all acdl-* AWS resources → nova-* across terraform (DynamoDB,
Secrets Manager, Lambda, SNS, SG, KMS alias, ECS, ECR, IAM user/policy,
state bucket, ALB, VPC/subnet names). Lambda default table names → nova-*
(D-111). State bucket backend → nova-tfstate (-migrate-state documented).
New docs/NOVA_AWS_MIGRATION.md runbook (staged migration + rollback).
New scripts/migrate_dynamodb_data.py (scan+copy, dry-run default).
acdl-deploy- → nova-deploy- role ARN in deploy workflows. Test fixtures
updated; terraform validate + pytest + run_ci.sh PASS.

---ci---
project: acdl
phase: 4
milestone: v1.15
status: execute
---/ci---

modules/l1/cloudfront/terraform/locals.tf

@@ -1,7 +1,7 @@
 locals {
   # OAC defaults (adapter previously hardcoded these).
-  oac_name              = "acdl-oac"
-  oac_origin_type       = "s3"
-  oac_signing_behavior  = "always"
-  oac_signing_protocol  = "sigv4"
+  oac_name             = "nova-oac"
+  oac_origin_type      = "s3"
+  oac_signing_behavior = "always"
+  oac_signing_protocol = "sigv4"
 }