Write release notes and migration guidance for v0.4.0

docs/roadmap/implementation.md

@@ -733,8 +733,8 @@ evidence describe the complete implemented feature.
    owners. Explain module selection, semantic version versus full tag, declared
    versus physical module identity, note/source/license links, path bases,
    boundaries, shared-file semantics, preparation, and receipt ownership.
-2. Write `docs/roadmap/next-release-notes.md` as the next release's pending notes
-   and migration guidance. A release version is not selected by this feature;
+2. Write the next release's pending notes and migration guidance.
+   A release version is not selected by this feature;
    keep the draft under roadmap ownership until release preparation assigns its
    `docs/releases/<version>.md` destination. Include API/profile updates, the
    preparation signature and tag field changes, receipt regeneration, CI mapping
@@ -764,7 +764,9 @@ implemented examples and canonical documentation agree with the current API.
 Gitea and internal ownership documents, recovery guidance, and maintained
 examples for module selection, full tags, path bases, shared files, preparation,
 and receipt ownership. Added pending next-release notes with migration guidance
-and corrected the current Go minimum facts. Audited acceptance coverage against
+and corrected the current Go minimum facts. Release preparation promoted those
+notes to [the v0.4.0 release note](../releases/v0.4.0.md).
+Audited acceptance coverage against
 the stage-owned tests and reviewed ReleaseKit's root release procedure against
 the adopted release policy; no new release gates were added. Verified
 `go test ./...`, `go run ./internal/apicheck`, local links and heading fragments