Add parahub-speed-control script (nftables set + tc HTB) for per-IP
speed shaping. Free tier 512kbps, paid tier unlimited. Heartbeat now
parses paid_clients from API response and syncs nftables set.
Replaced sqm-scripts/kmod-sched-cake/luci-app-sqm packages with
tc-full/kmod-ifb/kmod-sched-htb. Section 8 of uci-defaults creates
init.d service for speed control instead of SQM config.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
