feat(cli): keep AWS deploy secrets off the runner

[m-mohamed]

Summary

• Stop the AWS deployment CLI runner from retrieving plaintext application secrets.
• Validate secret values inside a short-lived ECS task during up and live checks.
• Sign private core requests inside AWS and exchange bounded request/response envelopes through S3.
• Keep qm plan metadata-only and side-effect-free.
• Preserve sanitized RunTask, stopped-task, and container failure diagnostics.

Security boundary

This removes routine plaintext secret retrieval from the CLI runner. It is not a sandbox against the deployment principal: a principal allowed to register arbitrary task definitions and pass the runtime role can still deploy code that exfiltrates runtime secrets. The README and Terraform tests state that boundary explicitly.

Verification

• Helper and Terraform tests: 29 passed.
• AWS plan/up/live transport test: passed.
• Packed npm artifact test: passed.
• CLI dispatch and deployment-layer tests: 47 passed.
• TypeScript typecheck.
• ESLint and Oxlint.
• Prettier.
• git diff --check.

An independent review verified that plan performs no ECS RunTask, service mutation, S3 write, DynamoDB lease, RDS snapshot, or ECR mutation; value validation remains fail-closed for up and live checks.