release: implement site registry v0.4 trust pipeline

docs/adr/0005-full-delta-release-identity.md

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+# ADR 0005: Full and delta release identities
+
+Status: Accepted, 2026-09-13.
+
+Each source object has its own digest. The selected coverage graph, including
+every active full, partition, base, and delta object and its precedence, has a
+separate digest bound into the generation receipt. A future distributed dataset
+delta must name exact base and target generation identities and preserve
+revocation continuity.
+
+An unauthenticated `latest` locator can be a convenience pointer, but never the
+trust root. Consumers authenticate a full receipt pin or publisher signature.
+
+Version 0.4 implements source-level full/partition/delta identity and cumulative
+publisher-signed emergency revocation overlays. General downloadable registry
+deltas remain a v0.6 distribution task because they also need mirror-independent
+base/target authentication and consumer transaction semantics.
+
+## Rejected alternatives
+
+Mutable releases and unpinned `latest` URLs permit substitution and rollback.
+Signing only a compressed archive makes alternate packaging unverifiable. Calling
+a source delta a registry delta would hide changes introduced by review policy,
+normalization, observations, or another provider.
+
+## Compatibility
+
+V2 receipts bind the selected coverage digest. Current pointers retain every
+legacy and vote revocation across activation. Emergency feeds apply only when
+their rules, policy, and reviewer-trust digests match the cached generation.