Merge batch-prediction-feature into main branch

[ByteBard58]

• Remove pyarrow and add python-multipart in requirements.txt
• Add batch prediction route in app.py
• Add sample csv file generator script in /dataset
• Rename sample generator script and add docstring
• Update .gitignore to ignore dataset/sample.csv
• Add pytest in requirements.txt
• Implement batch prediction feature with CSV file upload and results display
• Add new tests to test the batch prediction feature
• Add batch prediction tab with results display and pie chart visualization
• Add 5MB CSV size validation and CSV format guide