docs(adr): ADR-0048 — semantic-reference metadata embeds in package docs

Specifies how a doc author shows a live flow/view/dashboard/object inside
package documentation without re-opening the MDX trust boundary banned by
ADR-0046 §3.4 / ADR-0025.

Core inversion: the author supplies only a NAME (data); the platform
supplies the COMPONENT (code). Extends ADR-0046 §3.4's protocol-link family
(flow://, view://, dashboard://, object://) — each resolves renderer-side to
a read-only, permission-scoped SchemaRenderer scoped to one metadata item,
accepting no author-supplied props.

Two guardrails: (a) read-only + permission-scoped against the current
viewer; (b) cross-package refs degrade to a render-time "not found" notice,
never coupling into install-time dependency resolution. Boundary stated on
one line: in-metadata → live embed (this ADR); conceptual → Mermaid
(deferred); author-written component code → never. Rejects inline SDUI JSON,
MDX, and author-supplied iframes. P3+ — depends on the §3.4 resolution layer
and read-only embeddable metadata-view components in objectui, neither built.

Status: Proposed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: os-zhuang