Replace upsert with findFirst + create/update pattern to avoid Prisma
unique constraint syntax issues. The @@unique constraint with a custom
name doesn't allow direct field-based queries in findUnique/upsert.
This approach maintains the same behavior without schema changes.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
hailin
4e201d3a66
