⚡ Bolt: Memoize Printify blueprint variant fetching

[merg357]

💡 What: Wrapped get_variants in printify_manager.py with @functools.lru_cache and converted the return type to an immutable tuple. Added inline comments explaining the rationale. Added the required functools import. Created journal entry at .jules/bolt.md documenting this caching learning.

🎯 Why: The bulk creation loop caused an N+1 network bottleneck by requesting the same static blueprint variants from the Printify API for every single image uploaded, even though the blueprint ID and provider ID are identical across loops for a given item type. Returning a tuple ensures downstream mutation cannot alter the shared cache state, and json cleanly serializes tuples to arrays implicitly.

📊 Impact: Significantly speeds up product creation (e.g. python3 printify_manager.py create or run) by eliminating redundant HTTP requests (and latency) per product iteration. For 25 items, it removes 25 identical API calls, saving potentially 5-15 seconds in latency alone.

🔬 Measurement: Run python3 printify_manager.py create with multiple designs and observe the reduced creation time and decreased API call volume compared to running without the cache.

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PR created automatically by Jules for task 698427306353595514 started by @merg357

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