Fix spurious timeout warnings for empty connections

[BenCodez]

Summary

• distinguish clean EOF from a socket that remains open without sending a vote payload
• treat zero-byte clean disconnects as benign debug events instead of timeout warnings
• preserve the existing two-second warning for genuinely silent open connections
• replace the polling loop with a blocking one-byte read and pushback

Tests

• clean close after handshake returns promptly with no warning
• silent open connection still logs the timeout warning
• delayed valid V1 payload still parses correctly and preserves the first byte

This addresses empty companion/probe connections such as the reported MinecraftIPList pattern without reducing visibility for actual stalled sockets.

AI disclosure: This pull request was created with assistance from AI.