Module bandwidth_loop 

Shared bandwidth measurement loop for download/upload tests.

Eliminates duplication between download.rs and upload.rs by providing a unified state for:

• Throttled speed sampling (20 Hz max)
• Peak speed tracking
• Progress bar updates
• Atomic byte counting

Each I/O operation (download chunk, upload round) calls record_bytes() to update shared state. Call finish() at the end to compute final results.

Structs

BandwidthLoopState

Shared state for a bandwidth test (download or upload).

BandwidthResult

Final result from a bandwidth test.