fix: improved code readability & efficiency in split.py

[brawncode]

I’ve made a few improvements to the code to enhance both its readability and performance.

• The process_range function now uses a list comprehension, making the code more compact and easier to follow.
• In read_csv, the entire list of data is returned at once using list(), simplifying data handling.
• For write_csv, I replaced the individual row writes with writerows(), so all data is written in one go, improving performance.
• The data processing in main has been optimized by replacing nested loops with the extend() method, which adds entire ranges in one step.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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