chore: replace zip file reader to io reader

[Mahesh Kamble (ma-gk)]

Description

Replaced fs.Read(buf) with io.ReadFull(fs, buf) in the zip archive unpack (Read) function.

Go's io.Reader.Read() is not guaranteed to fill the entire buffer in a single call — it may return fewer bytes than requested even before EOF. For large files inside a ZIP archive, this results in truncated/partial data padded with null bytes.

io.ReadFull loops internally until exactly len(buf) bytes are read, ensuring complete data extraction.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation and I have updated the documentation accordingly.
• I have added tests to cover my changes.