⚡ Remove artificial delay in batch conversion

[paul0728]

💡 What: Replaced the artificial setTimeout(..., 50) delay per-image with a setTimeout(..., 0) UI yielding tick during batch processing.
🎯 Why: The 50ms delay caused significant unnecessary overhead. With a large number of files, this delay compounded heavily, slowing down batch conversions. Replacing it with a 0ms tick resolves this while still keeping the UI responsive.
📊 Measured Improvement: Simulated processing 100 dummy files. Performance time decreased significantly from ~5300ms to ~700ms.

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PR created automatically by Jules for task 6918276252745766752 started by @paul0728

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