feat: add Windows support using netsh for IP blocking

[Satvik-Singh192]

Description

This pull request lays the groundwork for Windows compatibility in the Simple Firewall project.

What was done

• Modified core initialization logic to detect Windows OS correctly.
• Ensured that the firewall initializes, runs, and shuts down gracefully on Windows 11 without crashing.
• Verified that the logging system and threads (cleanup, statistics) function normally.
• Tested CLI commands like --create-config and --stats to confirm cross-platform behavior.

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Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

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Issues

Fixes #2 — "[Feature]: Add Windows Support using netsh for IP Blocking"

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Checklist

• I have read the Contributing Guidelines.

[utkarshkgithub]

@Satvik-Singh192 Can you also verify if the program execution has administrator rights or not before further checks, also
use this consistent return value
def _get_default_interface(self) -> str: try: ......... return physical_interfaces[0] if physical_interfaces else 'eth0' except Exception: return ''
use this
return names[0] if names else 'Ethernet' #consistent naming
also add in README.md how to run this program in windows which would be preferably be like first step opening cmd as administrator , then navigating to the folder , then activating virtual env then running python main.py , also add requirements-windows.txt file for platform specific requirements, then check it if it is working fine in windows

[Satvik-Singh192]

@utkarshkgithub yes sir, i verified that we check if the program execution has administrator rights . also fixed the consistent return value . i also added instructions on how to run on windows in readme. i did add windows-requirements.txt but we dont use any external library which is exclusive for windows support. we only use prebuilt libraries and psutil is needed irrespective of the platform