⚡ Bolt: optimize path containment check

[thirdeyenation]

💡 What: Replaced os.path.commonpath with a string startswith comparison in is_in_dir.
🎯 Why: os.path.commonpath allocates lists and splits paths internally, causing unnecessary overhead for simple containment checks.
📊 Impact: Reduces path containment check execution time by ~66% (3x faster).
🔬 Measurement: Benchmark script comparing os.path.commonpath vs startswith across 100k iterations (0.70s vs 0.23s).

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PR created automatically by Jules for task 11107453636509341310 started by @thirdeyenation

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