Add compression ratio logging for rotated pcap uploads

[Copilot]

This updates the compression/upload path to include compression ratio details in the existing log stream. The new log entry makes it easier to see how effectively each rotated pcap was compressed before upload.

• Compression logging

  • Capture original and compressed file sizes in compressAndUpload
  • Log a single post-compression summary with source file, compressed file, byte sizes, and ratio

• Edge-case handling

  • Report ratio unavailable for zero-byte input or zero-byte compressed output
  • Differentiate empty input vs. empty compressed file in the log text

• Focused coverage

  • Add unit tests for compression stats formatting, including normal and zero-size cases

Example log output:

log.Printf("Compression complete: %s", compressionStats)
// capture.pcap -> capture.pcap.bz2 (1024 bytes -> 256 bytes, ratio 4.00:1)

Original prompt

Update repository FastNetMon/cloud_pcap to add logic that prints the compression ratio in the log file. Investigate where compression/upload logging currently happens, implement logging of the compression ratio in an appropriate place, and create a pull request with the change. Keep the existing logging style and ensure the new log output is clear and useful.

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User: Add logic to print comprssion ratio in log file

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