⚡ Bolt: [performance improvement]

[Dev22603]

💡 What: Replaced sequential await calls with Promise.all for updating product stocks within the createFromCart Prisma transaction in Backend/src/repositories/order.repositories.ts.
🎯 Why: Executing sequential await inside a transaction loop blocks the event loop and slows down the transaction, while Promise.all lets Prisma handle these independent queries concurrently.
📊 Impact: Reduces overall latency of the database transaction and database update completion by eliminating sequential network round-trips.
🔬 Measurement: Verify transaction execution time when checking out with a cart that has multiple items.

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PR created automatically by Jules for task 15856898563200581427 started by @Dev22603

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