fix(cli): reject unknown profile use instead of poisoning the default

[ankitranjan7]

webcmd profile use __audit_nope__ wrote that string as the default Cloak profile and exited 0. Later browser commands then ran against a profile that does not exist.

After

$ webcmd profile use __audit_nope__
# stderr, exit 2
ok: false
error:
  code: ARGUMENT
  message: No profile matches "__audit_nope__". Valid profiles: work, ctx_live
  help: |
    usage: webcmd profile use <alias|contextId>
    example: webcmd profile use work

Membership is the same set profile list shows: connected daemon profiles, saved aliases, and the current default. A saved alias still works when the daemon is down. Unknown names no longer persist.

Hosted impact

Hosted impact: A — no hosted impact
Trigger: none
Why: local Cloak `profile use` only. Hosted already rejects use/rename and exposes list/delete via /v1/profiles.
Sequencing: none

Verification

• npx tsc --noEmit — clean
• npx vitest run --project unit src/browser/profile.test.ts src/cli.test.ts — 146 passed

[github-actions]

🟠 Maintainer review suggested — low confidence

The automated review could not reach a fully supported conclusion.

Limitations

• The automated review returned an invalid structured result.

This review is advisory and does not block merging.