⚡ Bolt: Optimize MGF file loading memory usage

[google-labs-jules]

💡 What: Replaced io.StringIO(mgf_file.read().decode('utf-8')) with io.TextIOWrapper(mgf_file, encoding='utf-8') in app.py.
🎯 Why: The previous method loaded the entire file into memory as bytes, then created a full string copy, causing a 3x memory spike relative to file size.
📊 Impact: Significantly reduces memory usage during file upload/parsing, allowing larger MGF files to be processed.
🔬 Measurement: Verified with reproduction script that TextIOWrapper yields identical results to StringIO for pyteomics.mgf. Note that mzTab loading remains unchanged due to known parser incompatibilities.

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PR created automatically by Jules for task 1801239153882835148 started by @erayfirat

[google-labs-jules]

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