Track: marketplace plugin intake (Mkt#3) + buyer protection (#177)

[ReBoticsAI]

Goal

Track the two-sided marketplace plugin trust work already filed:

1. Intake (verify before list): GodMode-Marketplace#3 — public repo, pinned SHA, reusable GitHub Actions as verification VMs
2. Buyer runtime: #177 — pinned install + plugin least privilege (+ optional true plugin sandbox later)

Part of #112 / track-b. Not a substitute for coding isolation Layers 1–4.

Acceptance

• Marketplace#3 deliverables done (or explicitly sliced)
• Marketplace buyer protection: pinned install + plugin runtime least privilege #177 first slice done (design note + pin at install + capability follow-up filed/done)
• Cross-links from MARKETPLACE.md / SECURITY.md

Out of scope

• Implementing either child entirely in this meta issue (work happens on Add LLAMA_EXTERNAL attach mode for host llama-server #3 / Marketplace buyer protection: pinned install + plugin runtime least privilege #177)
• Design: path to Cursor-Cloud-like VM-grade coding isolation #172 job VMs