Enhance bridge protocol support: add KNX protocol to BridgeProtocolKind and update conversion functions

Signed-off-by: Tony <tonylu@tony-cloud.com>

include/bridge_model.hpp

@@ -10,6 +10,7 @@ enum class BridgeProtocolKind {
   mqtt = 1,
   modbus = 2,
   bacnet = 3,
+  knx = 4,
 };
 
 enum class BridgeObjectType {

src/bridge_model.cpp

@@ -221,6 +221,8 @@ const char* bridgeProtocolKindToString(BridgeProtocolKind kind) {
       return "modbus";
     case BridgeProtocolKind::bacnet:
       return "bacnet";
+    case BridgeProtocolKind::knx:
+      return "knx";
     case BridgeProtocolKind::unknown:
     default:
       return "unknown";
@@ -232,6 +234,7 @@ BridgeProtocolKind bridgeProtocolKindFromString(const std::string& value) {
   if (normalized == "mqtt") return BridgeProtocolKind::mqtt;
   if (normalized == "modbus") return BridgeProtocolKind::modbus;
   if (normalized == "bacnet") return BridgeProtocolKind::bacnet;
+  if (normalized == "knx") return BridgeProtocolKind::knx;
   return BridgeProtocolKind::unknown;
 }