refactor: 网关消除魔法值，scope/事件/请求头/MCP 协议等改为枚举与常量

- 新增 ScopeMatcher、GatewayAuthorities、JwtClaims、GatewayHeaders、InternalPaths、McpProtocol/McpToolArgs 等常量与枚举
- Webhook 消息体改用 ObjectMapper 构建，修复原先仅转义引号的问题
- 管理接口与 OpenAPI 控制器的默认值、响应字段、演示数据集中到 AdminDefaults / OpenApiFields

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/main/java/com/iot/gateway/oauth/OpenScopeEnum.java

@@ -12,10 +12,16 @@ import java.util.Map;
 @Getter
 public enum OpenScopeEnum {
 
-    DEVICE_READ("device.read", "设备台账读取", "允许拉取租户名下设备台账、在线状态与点位元数据", "设备资产", "LOW"),
-    TELEMETRY_READ("telemetry.read", "实时遥测召测", "允许实时读取料筒温度、射胶压力、螺杆转速及能耗电流等实时点位", "工况监控", "LOW"),
-    ALARM_READ("alarm.read", "故障告警检索", "允许检索产线设备的未确认告警、严重级别及历史故障原因", "异常告警", "LOW"),
-    DEVICE_CONTROL("device.control", "设备反向控制", "高危权限！允许向边缘设备下发启停控制与工艺参数反写指令", "反向控制", "HIGH");
+    DEVICE_READ(OpenScopeEnum.CODE_DEVICE_READ, "设备台账读取", "允许拉取租户名下设备台账、在线状态与点位元数据", "设备资产", "LOW"),
+    TELEMETRY_READ(OpenScopeEnum.CODE_TELEMETRY_READ, "实时遥测召测", "允许实时读取料筒温度、射胶压力、螺杆转速及能耗电流等实时点位", "工况监控", "LOW"),
+    ALARM_READ(OpenScopeEnum.CODE_ALARM_READ, "故障告警检索", "允许检索产线设备的未确认告警、严重级别及历史故障原因", "异常告警", "LOW"),
+    DEVICE_CONTROL(OpenScopeEnum.CODE_DEVICE_CONTROL, "设备反向控制", "高危权限！允许向边缘设备下发启停控制与工艺参数反写指令", "反向控制", "HIGH");
+
+    /** 编码常量，供 @PreAuthorize 等必须是编译期常量的注解表达式引用 */
+    public static final String CODE_DEVICE_READ = "device.read";
+    public static final String CODE_TELEMETRY_READ = "telemetry.read";
+    public static final String CODE_ALARM_READ = "alarm.read";
+    public static final String CODE_DEVICE_CONTROL = "device.control";
 
     private final String code;
     private final String name;