Accept ADR 0052 — a step that runs once before a container

The run-once lifecycle primitive: run-once:true on the existing container shape,
gated by declaration order + exit 0, idempotent by digest. No new host shape, no
arbitrary command — strictly less powerful than an action. Resolves issue 037.
Verified sound and faithful (ADR 0005/0047); status proposed->accepted.

02-DECISIONS/0052-a-step-that-runs-once-before-a-container.md

@@ -1,6 +1,6 @@
 ---
 topic: what runs on it
-status: proposed
+status: accepted
 date: 2026-09-05
 deciders: jochen
 reconstructed: false

02-DECISIONS/README.md

@@ -120,7 +120,7 @@ python3 00-META/checks/index.py            fail if stale
 - **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)
-- **0052** — [An init step is a container run once to completion, gating what follows](0052-a-step-that-runs-once-before-a-container.md)  *(proposed)*
+- **0052** — [An init step is a container run once to completion, gating what follows](0052-a-step-that-runs-once-before-a-container.md)
 
 ### How it is built