fix: support IPv6 connection monitor traceroute

[itsDNNS]

Summary

• add dual-stack ICMP traceroute support for IPv6 targets
• keep the helper output format and existing IPv4 behavior compatible
• preserve the setuid privilege boundary by opening raw sockets before DNS resolution and resolving only after dropping privileges
• add regression coverage for IPv6 parsing, helper source behavior, strict helper compilation, and privilege-ordering safety

Tests

• pytest tests/modules/connection_monitor/test_traceroute_probe.py tests/modules/connection_monitor/test_probe.py
• pytest tests/modules/connection_monitor
• gcc -O2 -Wall -Wextra -Werror -o /tmp/docsight-traceroute-helper.XXXXXX tools/traceroute_helper.c
• git diff --check

Closes #363