Add subnet broadcast discovery for CrossPoint WS

Implements automatic discovery of local broadcast addresses by querying network interfaces. The function filters out localhost addresses and calculates broadcast addresses for each valid network interface, enabling CrossPoint WebSocket discovery across multiple subnets.

crosspoint_reader/ws_client.py

@@ -189,6 +189,21 @@ def _broadcast_from_host(host):
     return '.'.join(parts)
 
 
+def _local_broadcast_addrs():
+    addrs = set()
+    try:
+        for info in socket.getaddrinfo(socket.gethostname(), None, socket.AF_INET):
+            ip = info[4][0]
+            if ip.startswith('127.'):
+                continue
+            bcast = _broadcast_from_host(ip)
+            if bcast:
+                addrs.add(bcast)
+    except Exception:
+        pass
+    return addrs
+
+
 def discover_device(timeout=2.0, debug=False, logger=None, extra_hosts=None):
     ports = [8134, 54982, 48123, 39001, 44044, 59678]
     local_port = 0
@@ -210,6 +225,10 @@ def discover_device(timeout=2.0, debug=False, logger=None, extra_hosts=None):
         pass
 
     targets = []
+    for bcast in _local_broadcast_addrs():
+        _log(logger, debug, f'[CrossPoint WS] discovery subnet broadcast {bcast}')
+        for port in ports:
+            targets.append((bcast, port))
     for port in ports:
         targets.append(('255.255.255.255', port))
     for host in extra_hosts or []: