feat(dns): emit multi_question event when qdcount>1

Packets with multiple questions were silently parsed at q0 only; the extra
questions were invisible.  Now emits multi_question at severity=5 with the
qdcount and q0 qname, then falls through and answers q0 normally.

decnet/templates/dns/server.py

@@ -672,6 +672,10 @@ def _handle(data: bytes, src_ip: str, src_port: int, transport: str) -> bytes |
     qtype_name  = _TYPE_NAMES.get(qtype, str(qtype))
     qclass_name = _CLASS_NAMES.get(qclass, str(qclass))
 
+    if qdcount > 1:
+        _log("multi_question", severity=5, src=src_ip, src_port=src_port,
+             transport=transport, qdcount=qdcount, qname=qname.rstrip("."))
+
     # Flood check runs on every packet (including CHAOS / transfer probes)
     _check_flood(src_ip, qtype_name)