Created MAC product registry and boundary model

Property	Value
description	Added the canonical product registry and explicit ownership boundaries across the MAC ecosystem.
version	0.4.0
type	Create
related	MAC, Ecosystem, Repo Boundaries

• Added a machine-readable product registry plus human-readable ecosystem registry docs.
• Defined the durable boundary model between mac, mac-docs, mac-mcp, product repos, and client repos.
• Recorded the active and planned mac-* products in one canonical governance source.