[B4] SDK vNext is private and app-tools install docs are not closed

[snowzane]

Current Finding

Public repository SDK vNext is private: true, version: 0.0.0-vnext.0, and preCutover: true. Public npm package presence for @nimiplatform/sdk does not prove vNext readiness. app-tools/README.md tells app authors to install @nimiplatform/sdk and @nimiplatform/kit, which must be reconciled with the vNext private posture.

Closure Evidence

• Public SDK/Kit package release evidence for the intended app-author path, or docs explicitly scoped to the older public package line.
• app-tools/README.md updated to match the real supported installation path.
• Public app consumption proof that does not rely on sibling link: dependencies.

Automation Boundary

Automation may update Evidence Status. Automation must not close this issue.

Decision Gate

Human review is required before Closed.