fix(cli): warn that fleet release does not tear down Cloud sandboxes

[NilotpalK]

Summary

A successful fleet release dispatch can leave a Cloud/provider sandbox running and incurring cost. Warn on stderr after a dispatched acknowledgement while retaining the existing single JSON document on stdout, including --delete-agent and --delete-agent --wait. This change does not request sandbox teardown.

Fixes #1922.

Adds seven regression tests, one RelayFlow bugfix proof case, a patch changelog entry, and tracked Trail records.

Test Plan

• Tests added/updated: all 18 release tests pass, including the seven new warning/output/failure regressions.
• Manual testing completed: ran the production command registration with the default output sinks and a stubbed remote release; separately captured stderr and parsed stdout as exactly one unchanged JSON document.
• npm run typecheck passes with Git's Unix tools on PATH for the existing build scripts.
• Changed source/proof files pass Prettier; ESLint reports no errors (existing complexity/depth/error-cause warnings, plus the release handler's complexity increases from 15 to 16).
• Proof manifest validation and git diff --check pass. The same runner observes bug on exact base c1ffabbc4 and fixed on exact head d4119014e; neither observation is selected from the proof arm.

Validation limits: the complete fleet file has 114 passing tests and one Windows path failure in --checkout keeps cross-repo --cwd inference on the actual checkout while using the explicit project workspace (/workspace-project versus C:\workspace-project). Unchanged base reproduces the same failure with 107 passing tests. The broader Windows suite (npm test --ignore-scripts -- --reporter=json) did not pass: its report records 3,040 passed, 342 failed, and 38 pending tests, and a worker ran out of heap memory. This PR remains draft pending maintainer validation on Linux. Fork PRs also require a maintainer to reproduce the branch and proof case in the upstream repository before the credential-bearing Cloud proof can run, per the case README.

RelayFlow Proof

• Change type: bugfix
• RelayFlow case: 1922-fleet-release-sandbox-warning

Screenshots

Not applicable; CLI warning only.

---

^{Need help on this PR? Tag @codesmith-bot with what you need.}

[coderabbitai]

Important

Draft PR not reviewed

Draft PRs are not automatically reviewed by default.

• Trigger a manual review

To automatically review draft PRs, update your CodeRabbit configuration:

reviews:
  auto_review:
    drafts: true

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}