feat: add incoming fw rules, fixed routes and improved docs

templates/nftables.conf.j2

@@ -15,6 +15,12 @@ table inet filter {
         # Allow LAN management access
         iif {{ lan_interface }} accept
 
+        # Allow incoming firewall rules
+{% for rule in incoming_firewall_rules %}
+        # {{ rule.name }}
+        iif {{ lan_interface }} ip saddr {{ rule.source }} {{ rule.protocol | default('tcp') }} dport {{ rule.port }} accept
+{% endfor %}
+
         # Allow ICMP
         ip protocol icmp accept
         ip6 nexthdr ipv6-icmp accept