Add security review for dockside-network-firewall.py

[struanb]

Motivation

• Provide a focused security review for install/usr/local/lib/dockside/dockside-network-firewall.py that records potential risks and prioritized hardening recommendations for running the daemon as root.

Description

• Add docs/security-review-dockside-network-firewall.md containing an executive summary, findings (notably unvalidated iptables-restore interpolation, management-socket authorization gaps, and unbounded per-connection thread spawning), and recommended mitigations; no runtime code paths were modified.

Testing

• Validated the firewall daemon's Python syntax with python3 -m py_compile install/usr/local/lib/dockside/dockside-network-firewall.py, which completed successfully.

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Codex Task