Add pscale deploy-request unblock

[no-itsbackpack]

When a Vitess deploy or revert fails, PlanetScale blocks the queue as a precaution. The dashboard button is “Unblock deploy queue”; this adds the same action to the CLI.

pscale deploy-request unblock mydb 12 --org myorg

Notes:

• Calls POST …/complete-deploy only when the deployment is in complete_error or complete_revert_error.
• Gated cutover (pending_cutover) is pointed at deploy-request apply. Deploy-check failures (error) are rejected — they are not an unblockable queue.

[cursor]

Risk: medium. Approved this PR; Bugbot completed with no findings and Security Agent was not running. No reviewers were assigned.

  

_{Sent by Cursor Approval Agent: cli-reviewer}