feat(moderation): route content moderation through configurable proxy server

Implements #2646: the risk-control content audit can now send OpenAI
Moderations requests through a proxy from IP Management - Proxy Servers.

Backend:
- ContentModerationConfig gains proxy_id (nil = direct, unchanged default)
- update semantics: null keeps, 0 clears, >0 selects (validated to exist)
- moderation calls build the client via the shared httpclient pool; proxy
  resolution failure surfaces as a moderation error and never silently
  falls back to direct connection
- proxy_id -> URL resolution cached 60s (single-entry, invalidated on
  config save) so the pre-block hot path does not hit the DB per request
- test-key endpoint accepts proxy_id too (null = saved config's proxy,
  0 = force direct), so input-key/saved-key tests exercise the same path
- proxy usage/inactivity logged (content_moderation.proxy_enabled /
  proxy_not_active) without leaking credentials

Frontend:
- ProxySelector in the risk-control basic settings tab, proxy list loaded
  non-blockingly; save and test payloads carry proxy_id; zh/en i18n

frontend/src/api/admin/riskControl.ts

@@ -14,6 +14,7 @@ export interface ContentModerationConfig {
   mode: ModerationMode
   base_url: string
   model: string
+  proxy_id: number | null
   api_key_configured: boolean
   api_key_masked: string
   api_key_count: number
@@ -66,6 +67,8 @@ export interface TestContentModerationAPIKeysPayload {
   base_url?: string
   model?: string
   timeout_ms?: number
+  // null/undefined 沿用已保存配置的代理；0 强制直连；>0 指定代理
+  proxy_id?: number
   prompt?: string
   images?: string[]
 }
@@ -90,6 +93,8 @@ export interface UpdateContentModerationConfig {
   mode?: ModerationMode
   base_url?: string
   model?: string
+  // undefined 不修改；0 清除（直连）；>0 指定代理
+  proxy_id?: number
   api_key?: string
   api_keys?: string[]
   api_keys_mode?: 'append' | 'replace'

frontend/src/i18n/locales/en/admin/channels.ts

@@ -286,6 +286,8 @@ export default {
       timeoutMs: 'HTTP Timeout (ms)',
       retryCount: 'Retry Count',
       sampleRate: 'Sample Rate',
+      proxy: 'Proxy Server',
+      proxyHint: 'Send moderation requests through the selected proxy (IP Management - Proxy Servers), useful when the egress IP is not supported by OpenAI. Defaults to direct connection.',
       recordNonHits: 'Record Non-Hits',
       recordNonHitsHint: 'When enabled, sampled non-hit request summaries are redacted before storage.',
       preHashCheck: 'Enable Pre-Hash Check',

frontend/src/i18n/locales/zh/admin/channels.ts

@@ -286,6 +286,8 @@ export default {
       timeoutMs: 'HTTP 超时 (ms)',
       retryCount: '失败重试次数',
       sampleRate: '采样率',
+      proxy: '代理服务器',
+      proxyHint: '审计请求经指定代理（IP管理-代理服务器）发出，适用于出口 IP 不受 OpenAI 支持的部署；默认直连。',
       recordNonHits: '记录未命中输入',
       recordNonHitsHint: '开启后会记录抽样但未命中的请求摘要，摘要会先脱敏再入库。',
       preHashCheck: '启用前置哈希比对',

frontend/src/views/admin/RiskControlView.vue

@@ -424,6 +424,11 @@
                   <span class="pointer-events-none absolute right-3 top-1/2 -translate-y-1/2 text-gray-400">%</span>
                 </div>
               </div>
+              <div>
+                <label class="input-label">{{ t('admin.riskControl.proxy') }}</label>
+                <ProxySelector v-model="configForm.proxy_id" :proxies="proxies" />
+                <p class="mt-2 text-xs leading-5 text-gray-500 dark:text-gray-400">{{ t('admin.riskControl.proxyHint') }}</p>
+              </div>
             </div>
 
             <div class="overflow-hidden rounded-xl border border-gray-100 bg-white shadow-sm dark:border-dark-700 dark:bg-dark-800">
@@ -1123,6 +1128,7 @@ import Select from '@/components/common/Select.vue'
 import Toggle from '@/components/common/Toggle.vue'
 import Pagination from '@/components/common/Pagination.vue'
 import ModelWhitelistSelector from '@/components/account/ModelWhitelistSelector.vue'
+import ProxySelector from '@/components/common/ProxySelector.vue'
 import { adminAPI } from '@/api/admin'
 import type {
   ContentModerationAPIKeyLoad,
@@ -1137,7 +1143,7 @@ import type {
   ModerationMode,
   UpdateContentModerationConfig,
 } from '@/api/admin/riskControl'
-import type { AdminGroup, SelectOption } from '@/types'
+import type { AdminGroup, Proxy, SelectOption } from '@/types'
 import { useAppStore } from '@/stores/app'
 import { extractApiErrorMessage } from '@/utils/apiError'
 import { formatDateTime as formatDateTimeValue } from '@/utils/format'
@@ -1205,6 +1211,7 @@ const activeSettingsTab = ref<SettingsTab>('basic')
 const groupSearch = ref('')
 const flaggedHashInput = ref('')
 const groups = ref<AdminGroup[]>([])
+const proxies = ref<Proxy[]>([])
 const logs = ref<ContentModerationLog[]>([])
 const status = ref<ContentModerationRuntimeStatus | null>(null)
 const testedApiKeyStatuses = ref<ContentModerationAPIKeyStatus[]>([])
@@ -1221,6 +1228,7 @@ const configForm = reactive({
   mode: 'pre_block' as ModerationMode,
   base_url: 'https://api.openai.com',
   model: 'omni-moderation-latest',
+  proxy_id: null as number | null,
   api_keys_text: '',
   api_key_configured: false,
   api_key_masked: '',
@@ -1695,6 +1703,7 @@ function applyConfig(config: ContentModerationConfig) {
   configForm.mode = config.mode
   configForm.base_url = config.base_url || 'https://api.openai.com'
   configForm.model = config.model || 'omni-moderation-latest'
+  configForm.proxy_id = config.proxy_id || null
   configForm.api_keys_text = ''
   configForm.api_key_configured = config.api_key_configured
   configForm.api_key_masked = config.api_key_masked || ''
@@ -1735,14 +1744,17 @@ function applyConfig(config: ContentModerationConfig) {
 async function loadAll() {
   loading.value = true
   try {
-    const [config, groupItems, runtimeStatus] = await Promise.all([
+    const [config, groupItems, runtimeStatus, proxyItems] = await Promise.all([
       adminAPI.riskControl.getConfig(),
       adminAPI.groups.getAll(),
       adminAPI.riskControl.getStatus(),
+      // 代理列表加载失败不阻塞风控页面（仅影响下拉可选项）
+      adminAPI.proxies.getAll().catch(() => [] as Proxy[]),
     ])
     applyConfig(config)
     groups.value = groupItems
     status.value = runtimeStatus
+    proxies.value = proxyItems
     if (Array.isArray(runtimeStatus.api_key_statuses)) {
       configForm.api_key_statuses = [...runtimeStatus.api_key_statuses]
       prunePendingDeleteAPIKeyHashes()
@@ -1786,6 +1798,8 @@ async function saveConfig() {
       mode: configForm.mode,
       base_url: configForm.base_url,
       model: configForm.model,
+      // 后端语义：0 清除代理（直连），>0 指定代理
+      proxy_id: configForm.proxy_id ?? 0,
       timeout_ms: Number(configForm.timeout_ms) || 3000,
       retry_count: Number(configForm.retry_count) || 0,
       sample_rate: Number(configForm.sample_rate) || 0,
@@ -1984,6 +1998,8 @@ async function testApiKeys(useInputKeys: boolean) {
       base_url: configForm.base_url,
       model: configForm.model,
       timeout_ms: Number(configForm.timeout_ms) || 3000,
+      // 与保存语义一致：0 强制直连，>0 指定代理，确保测试与实际审计走同一条链路
+      proxy_id: configForm.proxy_id ?? 0,
       prompt: moderationTestPrompt.value,
       images: moderationTestImages.value,
     })

frontend/src/views/admin/__tests__/RiskControlView.spec.ts

@@ -12,6 +12,7 @@ const {
   getStatus,
   listLogs,
   getGroups,
+  getProxies,
   showError,
   showSuccess,
 } = vi.hoisted(() => ({
@@ -20,6 +21,7 @@ const {
   getStatus: vi.fn(),
   listLogs: vi.fn(),
   getGroups: vi.fn(),
+  getProxies: vi.fn(),
   showError: vi.fn(),
   showSuccess: vi.fn(),
 }))
@@ -39,6 +41,9 @@ vi.mock('@/api/admin', () => ({
     groups: {
       getAll: getGroups,
     },
+    proxies: {
+      getAll: getProxies,
+    },
   },
 }))
 
@@ -73,6 +78,7 @@ const baseConfig = (): ContentModerationConfig => ({
   mode: 'pre_block',
   base_url: 'https://api.openai.com',
   model: 'omni-moderation-latest',
+  proxy_id: null,
   api_key_configured: false,
   api_key_masked: '',
   api_key_count: 0,
@@ -198,6 +204,7 @@ describe('admin RiskControlView', () => {
     getStatus.mockResolvedValue(runtimeStatus())
     listLogs.mockResolvedValue({ items: [], total: 0, page: 1, page_size: 20, pages: 1 })
     getGroups.mockResolvedValue([])
+    getProxies.mockResolvedValue([])
     updateConfig.mockImplementation(async (payload: UpdateContentModerationConfig) => ({
       ...baseConfig(),
       ...payload,
@@ -221,6 +228,7 @@ describe('admin RiskControlView', () => {
           Toggle: true,
           Pagination: true,
           ModelWhitelistSelector: ModelWhitelistSelectorStub,
+          ProxySelector: true,
         },
       },
     })
@@ -254,6 +262,7 @@ describe('admin RiskControlView', () => {
           Toggle: true,
           Pagination: true,
           ModelWhitelistSelector: ModelWhitelistSelectorStub,
+          ProxySelector: true,
         },
       },
     })
@@ -294,6 +303,7 @@ describe('admin RiskControlView', () => {
           Toggle: true,
           Pagination: true,
           ModelWhitelistSelector: ModelWhitelistSelectorStub,
+          ProxySelector: true,
         },
       },
     })
@@ -361,6 +371,7 @@ describe('admin RiskControlView', () => {
           Toggle: true,
           Pagination: true,
           ModelWhitelistSelector: ModelWhitelistSelectorStub,
+          ProxySelector: true,
         },
       },
     })