SyncPricelistsIfNeeded was called synchronously in Create(), blocking
the HTTP response for several seconds while pricelist data was fetched.
Users clicking multiple times caused 6+ duplicate configurations.
- Run SyncPricelistsIfNeeded in a goroutine so Create() returns immediately
- Add TryLock mutex to SyncPricelistsIfNeeded to skip concurrent calls
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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