revise ComNet paper and experiments for resubmission

[fabracht]

Paper, experiment infrastructure and analysis as submitted to Computer Networks on 2026-09-26.

• Experiment 3 rerun with per-packet loss on a forwarding VM (runner/planner phases, router netem and monitoring, kernel pin), plus paced, capped and build-comparison phases
• Acceptance, fold, paced, capped and build-comparison analysis scripts; updated figure scripts
• Revised manuscript, figures (renumbered to match the PDF) and references
• common_parallel.sh reads GCP_PROJECT/GCP_ACCOUNT from the environment or gcloud config instead of hardcoding them

Data: https://doi.org/10.5281/zenodo.19098819