[Base] Add +form-upgrade shortcut

Prerequisites

• I searched existing issues and discussions, this is not already proposed.
• This is a concrete, actionable proposal, not a vague wish.

Problem or motivation

The Base domain can create and manage forms (+form-create, +form-update, questions, share, submit) but cannot upgrade a legacy form to the new form version. The platform endpoint exists:

POST /open-apis/bitable/v1/apps/:app_token/tables/:table_id/forms/:form_id/upgrade

Proposed solution

One shortcut:

• +form-upgrade --base-token --table-id --form-id --form-name --display-mode (risk: write, scope: base:form:update)

Notes from verifying against a live tenant and the official Go SDK model:

• display-mode accepts exactly traditional or one_question_per_page. Anything else fails field validation (99992402).
• The response carries only the upgraded form id under data.form.id (per the SDK's UpgradeAppTableFormRespData), not a full form object.
• Forms already on the new version return 1254128 with a clear message, which is also the expected error path in tests.
• Honest test limitation: legacy forms can no longer be created through the API, so a live E2E test can cover auth, request shape, and the 1254128 error path, but the positive upgrade path can only be exercised on a legacy form created earlier in the UI.

Alternatives considered

Recreate the form from scratch with +form-create and delete the legacy one. That loses share links and any existing responses, so it is not equivalent for a form that is already in use.

Start by reading the existing +form-create and +form-update shortcuts and their Base form tests, then trace how they construct requests and validate flags. Done means +form-upgrade accepts the listed options, enforces the documented display modes and write scope, returns the upgraded form id, and covers the 1254128 error path; the positive live upgrade path may require a legacy form created in the UI.