fix(release): clarify roast v10 compatibility

[AsperforMias]

Summary

• remove real account and repository identifiers from the roast regression fixture and rollout plan
• represent an unchanged collection version with one canonical v4 read entry rather than a duplicate v4 fallback
• require a previous collection entry only when the collection version actually changes

Non-impact

• does not alter the existing v5/v5/v3 emergency DB fallback
• does not change scan, persistence, scoring, or roast runtime behavior

Validation

• pnpm test (509 tests)
• pnpm typecheck
• pnpm lint
• pnpm exec tsx scripts/check-release-versions.mts --base-ref upstream/main
• git diff --check

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