Follow AWS Lambda concurrency quota increase

While verifying Task 13567 on dev (2026-11-04), `ensure_function` failed at the reserved-concurrency step: `lambda refused PutFunctionConcurrency (HTTP 400): InvalidParameterValueException — Specified ReservedConcurrentExecutions for function decreases account's UnreservedConcurrentExecution below its minimum value of [10]`. The apps account (jaah-apps) still has 10 concurrent executions (Service Quotas L-B99A9384 = 10.0). The 1000 requested by `infra/jaah/terraform/org/apps-account.tf` (`aws_servicequotas_service_quota.apps_lambda_concurrency`) shows `CASE_OPENED` since 2026-11-03. Until AWS grants it, no Easy Mode app can be provisioned, because every app reserves concurrency. - Follow the AWS support case for the quota increase through to approval, or escalate it. - Consider making the provision step fail with a readable "the apps account's concurrency quota is not granted yet" reason instead of the raw AWS error. Out of scope: changing the per-app concurrency design. Done means: - `aws service-quotas get-service-quota --service-code lambda --quota-code L-B99A9384` in the apps account reports at least 1000. - A dev Easy Mode app provisions past its function step.

Merged #7965 (deploy green): provisioning now says the apps account's Lambda concurrency quota isn't granted instead of the raw AWS error. Quota still 10; AWS case 179373826700029 escalated with justification. Deferred: quota ≥1000 + dev app provision check await AWS approval.