fix(firmware): Three critical bugs found during MT3000 testing

1. Add yggdrasil init script (procd) — OpenWrt 25.x package doesn't
   include one, causing uci-defaults to fail on `/etc/init.d/yggdrasil
   enable` with set -e, leaving script in /etc/uci-defaults/ to re-run
   every boot and overwrite all config changes.

2. Delete default br-lan/lan before creating br-private — both bridges
   competing for eth0/eth1 port, preventing LAN cable access.

3. Per-device port mapping via /etc/parahub/port_map — filogic devices
   (MT3000, MT6000, WR3000) have eth0=WAN, eth1=LAN (opposite of
   qualcommax/ath79). Build.sh writes PORT_MAP, uci-defaults reads it.

Also: remove `set -e` from uci-defaults (too fragile for first-boot),
add SSH/HTTP firewall rules on yggdrasil zone for remote management.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

files/etc/init.d/yggdrasil

@@ -0,0 +1,17 @@
+#!/bin/sh /etc/rc.common
+
+START=95
+STOP=10
+
+USE_PROCD=1
+CONF_FILE="/etc/yggdrasil.conf"
+
+start_service() {
+	[ -f "$CONF_FILE" ] || return 1
+	procd_open_instance
+	procd_set_param command /usr/sbin/yggdrasil -useconffile "$CONF_FILE"
+	procd_set_param respawn
+	procd_set_param stdout 1
+	procd_set_param stderr 1
+	procd_close_instance
+}