Accept ADR 0051 — shared data is the operator's; a module is granted access

Your decision, ratified: the media library (and shared/pre-existing data) is
operator-owned and external; a module declares access, not ownership; the host
mounts but owns nothing (no create/chown/reconcile/remove); an absent accessed
path is refused clearly; several accessors co-resolve. Status proposed->accepted;
index regenerated (records + index checks pass). Implementation lives on the code
branches (mesh-control/catalog/host), held for merge after the convergence fix.

Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF

02-DECISIONS/README.md

@@ -119,7 +119,7 @@ python3 00-META/checks/index.py            fail if stale
 - **0048** — [A provider creates the credential the mesh minted, and seals nothing](0048-a-provider-creates-the-credential-the-mesh-minted.md)
 - **0049** — [A consumer's identity is bounded by the tightest backend that must accept it](0049-a-consumers-identity-fits-the-tightest-backend.md)
 - **0050** — [Model access is vendor-agnostic, and a vendor is an adapter](0050-model-access-is-vendor-agnostic.md)
-- **0051** — [Shared data is the operator's, and a module is granted access to it](0051-shared-data-is-the-operators.md)  *(proposed)*
+- **0051** — [Shared data is the operator's, and a module is granted access to it](0051-shared-data-is-the-operators.md)
 
 ### How it is built