fix(BREV-9479): inline lifecycle script body when deploying launchable via CLI

[harshsharmanv]

Summary

• brev create <name> --launchable <id> failed with rpc error: code = Internal desc = lifecycle script is empty whenever the launchable had a lifecycle script attached.
• The launchable GET endpoint returns lifeCycleScriptAttr as an {id, name} reference; the script body is stored in blobstore and is not inlined, passed on user's request but not returned on get or list. The backend's create-workspace path requires the client to supply the script content.
• The Brev Console handles this by calling GET /api/launchable/lifecycle-script?envId=...&scriptId=... and inlining the response into attrs.script before sending create request. The CLI did not, it forwarded the reference as-is.

This PR makes the CLI mirror the Brev Console:

1. New store method AuthHTTPStore.GetLaunchableLifeCycleScript hitting the same endpoint the Console uses.
2. fetchAndDisplayLaunchable now calls inlineLaunchableLifeCycleScript, which fetches and inlines the body when attr.ID is set and attr.Script is empty.
3. Brev client gate the fetch on id presence, so launchables with no lifecycle script remain unaffected — the field stays nil, omitempty drops it from the POST, and the backend's hasLifecycleScript returns false (no validation).