Improve Accurancy of diff hunk parsing in parseAllHunks

[Saga4]

closes #505
Desc:
🔍 Problem
The existing implementation of parseAllHunks was incorrectly calculating line ranges when processing certain GNU diff formats. This caused issues with:

• Inaccurate line number reporting in hunks
• Missing context within modified ranges
• Incorrect handling of adjacent changes

💡 Solution
This PR rewrites the parseAllHunks function to use a more robust multi-pass approach:

• First identifies the exact modified line range by using actual line numbers from the diff data
• Collects both added lines and normal lines within the modified range
• Reconstructs the changed/added content with proper line ordering
• Explicitly handles edge cases like "No newline at end of file" markers

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Fixes #<issue_number_goes_here> 🦕

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