⚡ Bolt: Optimize get_files IO Utilities

[georgi]

💡 What: Replaced iterative string concatenation (+=) with list.append() and "".join() in get_content(), and replaced list additions (+=) with .extend() in get_files().

🎯 Why: In Python, string concatenation using += inside loops creates O(N^2) memory reallocation operations due to string immutability. Replacing it with list aggregation and join reduces the time complexity to O(N).

📊 Impact: Reduces CPU and memory footprint linearly when reading nested directories containing large numbers of text assets or when deeply recurring through files.

🔬 Measurement: Verifiable by executing code with massive directory paths, where get_content() avoids intermediate copy creation.

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PR created automatically by Jules for task 612808861715949373 started by @georgi

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