fix: Check protocol server status before attempting connections in signals endpoint

- Added check for settings.opcua_enabled and settings.modbus_enabled before initializing ProtocolDataCollector
- This prevents connection attempts when protocol servers are disabled in production
- Reduces error logs and improves performance

src/dashboard/api.py

@@ -620,6 +620,8 @@ async def get_signals():
         
         signals = []
         
+        # Check if protocol servers are enabled before trying to connect
+        if settings.opcua_enabled or settings.modbus_enabled:
             # Try to get data from protocol servers, fallback to mock data if servers are not available
             try:
                 # Initialize protocol data collector
@@ -648,6 +650,10 @@ async def get_signals():
                 logger.error("failed_to_get_protocol_data", error=str(e), fallback="using_mock_data")
                 # Fallback to mock data
                 signals = await _generate_mock_signals(stations, pumps_by_station)
+        else:
+            # Protocol servers are disabled, use mock data
+            logger.info("protocol_servers_disabled", fallback="using_mock_data")
+            signals = await _generate_mock_signals(stations, pumps_by_station)
         
         # Add system status signals
         signals.extend([