## Summary
Fixes a race condition where a server could have no version marked as
`isLatest` if the database operations failed independently.
## Changes
- **CreateServer signature**: Now accepts `oldLatestVersionID` parameter
to atomically unmark previous latest version
- **PostgreSQL implementation**: Uses a transaction to ensure UPDATE
(unmark old latest) and INSERT (create new version) happen atomically
- **Service layer**: Maintains `WithPublishLock` for concurrent
operation serialization
- **Two-level protection**: Advisory lock prevents races, transaction
ensures atomicity
## Test plan
- [x] Existing race condition tests pass
- [x] Integration tests pass
- [x] Unit tests pass
🤖 Generated with [Claude Code](https://claude.ai/code)
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Co-authored-by: Claude <noreply@anthropic.com>
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