⚡ Bolt: Memoize variant fetching with LRU cache

[merg357]

💡 What: Memoized third-party API variant queries using @functools.lru_cache and casted the return value to an immutable tuple.
🎯 Why: Prevents N+1 network requests during iterative product creation loops, preventing redundant API calls.
📊 Impact: Eliminates redundant HTTP requests, drastically speeding up bulk generation.
🔬 Measurement: Time the product generation loop before and after; notice significantly reduced network wait time.

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PR created automatically by Jules for task 11443094112066810654 started by @merg357

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