iperf3 Server Improvements
- Better logging for iperf3 server lifecycle - Now logs exit codes and runtime when the server exits, with clear warnings when it exits immediately (e.g., port already in use)
- Exponential backoff for restart failures - When iperf3 can't start (e.g., port conflict), applies exponential backoff (1s, 2s, 4s, 8s, 16s) and stops after 5 consecutive failures instead of spinning in a tight restart loop
Other Fixes
- Fix version check for pre-release versions (alpha/beta/rc)
- Clarify iperf3 install instructions are for client device