feat(firewall): report the gateway a filter rule policy-routes to

get_firewall_rules read searchRule but dropped the rule's gateway. A pass
rule with a gateway hands what it matches to that gateway, local
destinations included, so it does not reach a host on another internal
network. Without the field a caller judging reachability reads a rule meant
for internet traffic as a hole into every server: on the first real box,
"pass UDP IOT -> any" via WAN_GW made 61 hosts look reachable from the IoT
segment (netOrk #575).

The rule dict gains "gateway", the gateway's name or "". It is an extra
field like floating and interface_label; the generic diff compares a fixed
field list and ignores it.

napalm_opnsense/opnsense.py

@@ -2444,6 +2444,10 @@ class OPNsenseDriver(OPNsensePingMixin, FirewallDriver):
         * ``floating``          — bool, rule applies across all interfaces
         * ``interface_label``   — human-readable interface description
         * ``is_group``          — bool, interface is an interface group
+        * ``gateway``           — the gateway a pass rule policy-routes to, or
+          ``""``. Such a rule sends what it matches to that gateway, local
+          destinations included, so it does not reach a host on another
+          internal network.
         """
         try:
             resp = self._get("/api/firewall/filter/searchRule?current=1&rowCount=-1")
@@ -2508,6 +2512,7 @@ class OPNsenseDriver(OPNsensePingMixin, FirewallDriver):
                 "log":              str(row.get("log", "0")) == "1",
                 "enabled":          str(row.get("enabled", "1")) == "1",
                 "category":         category,
+                "gateway":          row.get("gateway", "") or "",
             })
 
         return sorted(result, key=lambda x: (x["floating"], x["is_group"], x["interface"], x["sequence"]))