⚡ Bolt: [performance improvement] Vectorize PHY byte parsing

[google-labs-jules]

💡 What: Replaced slow Python for loops and repeated struct.unpack_from calls in phy_reader.py with struct.iter_unpack using list comprehensions and format pad chars (x).

🎯 Why: Reading collision bounds iteratively in pure Python via unpack_from is severely bottlenecked by loop overhead and function calls. Moving this logic to iter_unpack pushes iteration down into C implementation, making initialization significantly faster.

📊 Impact: Reduces collision data parse time in Python environments (e.g. reachability checks, regression tools) by skipping loop overhead.

🔬 Measurement: Check the time spent instantiating CollisionWorld in check_regression_faces.py or observe script determinism is unchanged when using identical datasets.

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PR created automatically by Jules for task 6006187635367614745 started by @legoj15

[google-labs-jules]

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