Fix flate corrupt input error when reading ZIP entries with gzran

[Copilot]

The Read function in archive_zip.go was incorrectly attempting to skip reading compressed bytes by seeking to a pre-computed offset, leaving zeros at the start of the buffer. This caused flate: corrupt input before offset 5 errors because deflate streams cannot be decoded from arbitrary offsets due to the sliding window compression mechanism.

Changes

• Remove incorrect compressed data skipping optimization in gozipArchiveEntry.Read()
• Always read entire compressed data before passing to gzran.NewDReader
• The gzran Index is still used for efficient seeking within the uncompressed output

Before (buggy)

compressedData := make([]byte, e.file.CompressedSize64)
f.(io.Seeker).Seek(lastCompressedOffset, io.SeekStart)
_, err := io.ReadFull(f, compressedData[lastCompressedOffset:])  // zeros before offset
fzr, err := gzran.NewDReader(bytes.NewReader(compressedData))   // fails: invalid data at start

After

compressedData := make([]byte, e.file.CompressedSize64)
_, err := io.ReadFull(f, compressedData)  // read complete stream
fzr, err := gzran.NewDReader(bytes.NewReader(compressedData))

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