Release ContentCloud v0.4.0

[wutongci]

Summary

• complete the V2 SubmissionRevision to client approval, ApprovedSnapshot, delivery, performance, rating, and lineage workflow
• add PostgreSQL migrations and V1 shadow snapshot backfill reporting
• update CLI, OpenAPI, console UI, development tooling, roadmap, plugin proposal, and release metadata
• make review grant verification/revocation/decision transitions concurrency-safe

Verification

• make check
• CONTENTCLOUD_TEST_DATABASE_URL=postgres://root@localhost:5432/contentcloud_codex_v2_test?sslmode=disable go test -race ./...
• pnpm --dir web test
• swagger-cli validate contracts/openapi.yaml
• node syntax checks for CLI and migration scripts
• git diff --check

Deployment

• no Docker
• no npm publish
• no ClamAV
• deploy server, worker, and web bundle to the existing systemd deployment after merge and GitHub Release