feat: 新增全局错误透传规则功能

支持管理员配置上游错误如何返回给客户端：
- 新增 ErrorPassthroughRule 数据模型和 Ent Schema
- 实现规则的 CRUD API（/admin/error-passthrough-rules）
- 支持按错误码、关键词匹配，支持 any/all 匹配模式
- 支持按平台过滤（anthropic/openai/gemini/antigravity）
- 支持透传或自定义响应状态码和错误消息
- 实现两级缓存（Redis + 本地内存）和多实例同步
- 集成到 gateway_handler 的错误处理流程
- 新增前端管理界面组件
- 新增单元测试覆盖核心匹配逻辑

优化：
- 移除 refreshLocalCache 中的冗余排序（数据库已排序）
- 后端 Validate() 增加匹配条件非空校验

frontend/src/i18n/locales/en.ts

@@ -3191,6 +3191,80 @@ export default {
       failedToSave: 'Failed to save settings',
       failedToTestSmtp: 'SMTP connection test failed',
       failedToSendTestEmail: 'Failed to send test email'
+    },
+
+    // Error Passthrough Rules
+    errorPassthrough: {
+      title: 'Error Passthrough Rules',
+      description: 'Configure how upstream errors are returned to clients',
+      createRule: 'Create Rule',
+      editRule: 'Edit Rule',
+      deleteRule: 'Delete Rule',
+      noRules: 'No rules configured',
+      createFirstRule: 'Create your first error passthrough rule',
+      allPlatforms: 'All Platforms',
+      passthrough: 'Passthrough',
+      custom: 'Custom',
+      code: 'Code',
+      body: 'Body',
+
+      // Columns
+      columns: {
+        priority: 'Priority',
+        name: 'Name',
+        conditions: 'Conditions',
+        platforms: 'Platforms',
+        behavior: 'Behavior',
+        status: 'Status',
+        actions: 'Actions'
+      },
+
+      // Match Mode
+      matchMode: {
+        any: 'Code OR Keyword',
+        all: 'Code AND Keyword',
+        anyHint: 'Status code matches any error code, OR message contains any keyword',
+        allHint: 'Status code matches any error code, AND message contains any keyword'
+      },
+
+      // Form
+      form: {
+        name: 'Rule Name',
+        namePlaceholder: 'e.g., Context Limit Passthrough',
+        priority: 'Priority',
+        priorityHint: 'Lower values have higher priority',
+        description: 'Description',
+        descriptionPlaceholder: 'Describe the purpose of this rule...',
+        matchConditions: 'Match Conditions',
+        errorCodes: 'Error Codes',
+        errorCodesPlaceholder: '422, 400, 429',
+        errorCodesHint: 'Separate multiple codes with commas',
+        keywords: 'Keywords',
+        keywordsPlaceholder: 'One keyword per line\ncontext limit\nmodel not supported',
+        keywordsHint: 'One keyword per line, case-insensitive',
+        matchMode: 'Match Mode',
+        platforms: 'Platforms',
+        platformsHint: 'Leave empty to apply to all platforms',
+        responseBehavior: 'Response Behavior',
+        passthroughCode: 'Passthrough upstream status code',
+        responseCode: 'Custom status code',
+        passthroughBody: 'Passthrough upstream error message',
+        customMessage: 'Custom error message',
+        customMessagePlaceholder: 'Error message to return to client...',
+        enabled: 'Enable this rule'
+      },
+
+      // Messages
+      nameRequired: 'Please enter rule name',
+      conditionsRequired: 'Please configure at least one error code or keyword',
+      ruleCreated: 'Rule created successfully',
+      ruleUpdated: 'Rule updated successfully',
+      ruleDeleted: 'Rule deleted successfully',
+      deleteConfirm: 'Are you sure you want to delete rule "{name}"?',
+      failedToLoad: 'Failed to load rules',
+      failedToSave: 'Failed to save rule',
+      failedToDelete: 'Failed to delete rule',
+      failedToToggle: 'Failed to toggle status'
     }
   },
 

frontend/src/i18n/locales/zh.ts

@@ -3362,6 +3362,80 @@ export default {
       failedToSave: '保存设置失败',
       failedToTestSmtp: 'SMTP 连接测试失败',
       failedToSendTestEmail: '发送测试邮件失败'
+    },
+
+    // Error Passthrough Rules
+    errorPassthrough: {
+      title: '错误透传规则',
+      description: '配置上游错误如何返回给客户端',
+      createRule: '创建规则',
+      editRule: '编辑规则',
+      deleteRule: '删除规则',
+      noRules: '暂无规则',
+      createFirstRule: '创建第一条错误透传规则',
+      allPlatforms: '所有平台',
+      passthrough: '透传',
+      custom: '自定义',
+      code: '状态码',
+      body: '消息体',
+
+      // Columns
+      columns: {
+        priority: '优先级',
+        name: '名称',
+        conditions: '匹配条件',
+        platforms: '平台',
+        behavior: '响应行为',
+        status: '状态',
+        actions: '操作'
+      },
+
+      // Match Mode
+      matchMode: {
+        any: '错误码 或 关键词',
+        all: '错误码 且 关键词',
+        anyHint: '状态码匹配任一错误码，或消息包含任一关键词',
+        allHint: '状态码匹配任一错误码，且消息包含任一关键词'
+      },
+
+      // Form
+      form: {
+        name: '规则名称',
+        namePlaceholder: '例如：上下文超限透传',
+        priority: '优先级',
+        priorityHint: '数值越小优先级越高，优先匹配',
+        description: '规则描述',
+        descriptionPlaceholder: '描述此规则的用途...',
+        matchConditions: '匹配条件',
+        errorCodes: '错误码',
+        errorCodesPlaceholder: '422, 400, 429',
+        errorCodesHint: '多个错误码用逗号分隔',
+        keywords: '关键词',
+        keywordsPlaceholder: '每行一个关键词\ncontext limit\nmodel not supported',
+        keywordsHint: '每行一个关键词，不区分大小写',
+        matchMode: '匹配模式',
+        platforms: '适用平台',
+        platformsHint: '不选择表示适用于所有平台',
+        responseBehavior: '响应行为',
+        passthroughCode: '透传上游状态码',
+        responseCode: '自定义状态码',
+        passthroughBody: '透传上游错误信息',
+        customMessage: '自定义错误信息',
+        customMessagePlaceholder: '返回给客户端的错误信息...',
+        enabled: '启用此规则'
+      },
+
+      // Messages
+      nameRequired: '请输入规则名称',
+      conditionsRequired: '请至少配置一个错误码或关键词',
+      ruleCreated: '规则创建成功',
+      ruleUpdated: '规则更新成功',
+      ruleDeleted: '规则删除成功',
+      deleteConfirm: '确定要删除规则 "{name}" 吗？',
+      failedToLoad: '加载规则失败',
+      failedToSave: '保存规则失败',
+      failedToDelete: '删除规则失败',
+      failedToToggle: '切换状态失败'
     }
   },
 

frontend/src/views/admin/AccountsView.vue

@@ -16,6 +16,16 @@
             @sync="showSync = true"
             @create="showCreate = true"
           >
+            <template #before>
+              <button
+                @click="showErrorPassthrough = true"
+                class="btn btn-secondary"
+                :title="t('admin.errorPassthrough.title')"
+              >
+                <Icon name="shield" size="md" class="mr-1.5" />
+                <span class="hidden md:inline">{{ t('admin.errorPassthrough.title') }}</span>
+              </button>
+            </template>
             <template #after>
               <!-- Auto Refresh Dropdown -->
               <div class="relative" ref="autoRefreshDropdownRef">
@@ -221,6 +231,7 @@
     <BulkEditAccountModal :show="showBulkEdit" :account-ids="selIds" :proxies="proxies" :groups="groups" @close="showBulkEdit = false" @updated="handleBulkUpdated" />
     <TempUnschedStatusModal :show="showTempUnsched" :account="tempUnschedAcc" @close="showTempUnsched = false" @reset="handleTempUnschedReset" />
     <ConfirmDialog :show="showDeleteDialog" :title="t('admin.accounts.deleteAccount')" :message="t('admin.accounts.deleteConfirm', { name: deletingAcc?.name })" :confirm-text="t('common.delete')" :cancel-text="t('common.cancel')" :danger="true" @confirm="confirmDelete" @cancel="showDeleteDialog = false" />
+    <ErrorPassthroughRulesModal :show="showErrorPassthrough" @close="showErrorPassthrough = false" />
   </AppLayout>
 </template>
 
@@ -252,6 +263,7 @@ import AccountGroupsCell from '@/components/account/AccountGroupsCell.vue'
 import AccountCapacityCell from '@/components/account/AccountCapacityCell.vue'
 import PlatformTypeBadge from '@/components/common/PlatformTypeBadge.vue'
 import Icon from '@/components/icons/Icon.vue'
+import ErrorPassthroughRulesModal from '@/components/admin/ErrorPassthroughRulesModal.vue'
 import { formatDateTime, formatRelativeTime } from '@/utils/format'
 import type { Account, Proxy, AdminGroup } from '@/types'
 
@@ -271,6 +283,7 @@ const showDeleteDialog = ref(false)
 const showReAuth = ref(false)
 const showTest = ref(false)
 const showStats = ref(false)
+const showErrorPassthrough = ref(false)
 const edAcc = ref<Account | null>(null)
 const tempUnschedAcc = ref<Account | null>(null)
 const deletingAcc = ref<Account | null>(null)