[Base] Add +dashboard-copy 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 covers dashboard CRUD (+dashboard-create, +dashboard-update, +dashboard-delete, blocks, share, arrange) but has no way to duplicate a dashboard. Duplicating is a common setup step when scaffolding several similar dashboards, and today agents must use the raw API:

lark-cli api POST /open-apis/bitable/v1/apps/<app_token>/dashboards/<block_id>/copy

Proposed solution

One shortcut:

• +dashboard-copy --base-token --block-id --name (risk: write, scope: base:dashboard:copy)

Notes from verifying against a live tenant:

• The docs list bitable:app as the required scope, but the granular base:dashboard:copy scope is accepted and works.
• Response carries the new dashboard block_id and name.
• --name is required by the API and validated as non-empty.

Alternatives considered

Keep using the raw api escape hatch. It works but skips scope preflight and dry-run, and the scope name (base:dashboard:copy vs the documented bitable:app) is easy to get wrong without a typed command declaring it.

Start by examining the existing Base dashboard shortcuts, especially +dashboard-create, +dashboard-update, and +dashboard-delete, then compare their handling with the documented POST /open-apis/bitable/v1/apps/<app_token>/dashboards/<block_id>/copy endpoint. Done means a typed +dashboard-copy command accepts --base-token, --block-id, and non-empty --name, declares base:dashboard:copy, and exposes the returned block_id and name with scope preflight and dry-run support.