feat: Replace SQM with per-client speed control for paid WiFi upgrade

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>

files/etc/uci-defaults/99-parahub-mesh

@@ -525,22 +525,26 @@ fi
 uci commit dhcp
 
 # ============================================================================
-# 8. SQM TRAFFIC SHAPING (Bumblebee only — guest 512 kbps limit)
+# 8. SPEED CONTROL (Bumblebee only — per-client shaping, paid Lightning upgrade)
 # ============================================================================
 
 if [ "$ROLE" != "bee" ]; then
-    uci batch <<-SQM_EOF
-set sqm.guest=queue
-set sqm.guest.enabled='1'
-set sqm.guest.interface='br-guest'
-set sqm.guest.download='512'
-set sqm.guest.upload='512'
-set sqm.guest.qdisc='cake'
-set sqm.guest.script='piece_of_cake.qos'
-set sqm.guest.linklayer='ethernet'
-set sqm.guest.overhead='44'
-SQM_EOF
-    uci commit sqm
+    chmod +x /usr/bin/parahub-speed-control
+
+    # Create init.d service for speed control
+    cat > /etc/init.d/parahub-speed <<'INITEOF'
+#!/bin/sh /etc/rc.common
+START=99
+start() { /usr/bin/parahub-speed-control init; }
+stop() {
+    tc qdisc del dev br-guest root 2>/dev/null
+    tc qdisc del dev br-guest ingress 2>/dev/null
+    ip link del ifb-guest 2>/dev/null
+    nft delete table inet parahub 2>/dev/null
+}
+INITEOF
+    chmod +x /etc/init.d/parahub-speed
+    /etc/init.d/parahub-speed enable
 fi
 
 # ============================================================================