Add web GUI, docs, scripts, and 5G router config

- Web app (Flask): status, config, firewall, logs, users, restart
- Docs: AT commands, deploy, DNS, quickstart, web GUI
- Scripts: connect, deploy, diag, healthcheck, modem-status, speedtest, status, troubleshoot
- Init and iptables: 5g-router, 5g-webgui, rules.v4
- CHANGELOG, TODO, REVISION; config and README updates

scripts/speedtest-5g.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+# Optional: run speedtest and append to log (for cron)
+# Requires: apk add speedtest-cli
+# Cron example: 0 */6 * * * /usr/local/bin/speedtest-5g.sh
+# Rev: 1  (see REVISION in repo root)
+
+LOG="/var/log/speedtest-5g.log"
+if command -v speedtest-cli >/dev/null 2>&1; then
+    echo "=== $(date -Iseconds) ===" >> "$LOG"
+    speedtest-cli --simple >> "$LOG" 2>&1
+    echo "" >> "$LOG"
+else
+    echo "$(date -Iseconds) speedtest-cli not installed" >> "$LOG"
+fi