feat(channel-monitor-v2): 补齐管理端配置、隐藏吞吐开关与测试

管理端 V2 配置面板与系统设置中的模式/隐藏 RPM·TPM 开关，纳入关键
vitest 与 Makefile 前端关键路径，覆盖门控与展示行为。

frontend/src/api/admin/settings.ts

@@ -670,7 +670,9 @@ export interface SystemSettings {
 
   // Channel Monitor feature switch
   channel_monitor_enabled: boolean;
+  channel_monitor_mode?: 'v1' | 'v2';
   channel_monitor_default_interval_seconds: number;
+  channel_monitor_hide_throughput?: boolean;
 
   // Available Channels feature switch
   available_channels_enabled: boolean;
@@ -961,7 +963,9 @@ export interface UpdateSettingsRequest {
 
   // Channel Monitor feature switch
   channel_monitor_enabled?: boolean;
+  channel_monitor_mode?: 'v1' | 'v2';
   channel_monitor_default_interval_seconds?: number;
+  channel_monitor_hide_throughput?: boolean;
 
   // Available Channels feature switch
   available_channels_enabled?: boolean;