Add rollback command to bb apps

[nathan-thillairajah]

Summary

bb apps deploy can publish a version, but the CLI had no way to reverse a bad deployment. This adds bb apps rollback <APP_ID> [--environment <ENVIRONMENT>] [--version-id <VERSION_ID>] and maps it directly to the Compose rollback endpoint.

Omitting --version-id asks Compose to select the previous active version. Passing one activates that uploaded version instead. The command uses the existing allowlisted control-plane client, safely encodes app IDs, preserves the server response, and does not add hidden polling. ready and debug also gain --environment so follow-up checks can target the same environment as the rollback.

Related issue

N/A. No matching open issue or PR found.

Testing

At commit 7c6bb2c5cee92f2a667c9935393405cf679f4043:

• cd bb-cli && source ../bin/activate-hermit && just check (143 unit, 75 bb E2E, 22 CLI E2E, and 6 acceptance tests)
• repository pre-commit and pre-push hooks (frontend checks, Tauri checks, formatting, and Clippy)

Live control-plane verification was not run because the local Builderlab CLI session is intentionally logged out. The route, request body, environment selection, and response behavior were verified against the current squareup/blockplat-compose source and covered with mocked process tests.

[morgmart]

🤖 Automated code review

REQUEST_CHANGES: the static four-lens review found no publishable changed-line defects, but this PR adds a meaningful user-facing CLI workflow and the supplied GitHub evidence contains no screenshot or short screen recording. Add visual evidence before approval. Supplied GitHub checks are currently pending with no reported check runs, so required checks still govern merge readiness.

Deterministic publication result: 0 blocking and 0 non-blocking inline finding(s) publishable; 0 duplicate(s) suppressed; 1 blocking screenshot-evidence requirement(s) in this review body.

🤖 Blocking · Screenshots needed

This PR changes a meaningful user-facing experience. Please add screenshots or a short screen recording so the visual result can be reviewed. Screenshots are review evidence; they do not replace accessibility, responsive, theme, localization, or behavior validation.