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/api/admin/errorPassthrough.ts

@@ -0,0 +1,134 @@
+/**
+ * Admin Error Passthrough Rules API endpoints
+ * Handles error passthrough rule management for administrators
+ */
+
+import { apiClient } from '../client'
+
+/**
+ * Error passthrough rule interface
+ */
+export interface ErrorPassthroughRule {
+  id: number
+  name: string
+  enabled: boolean
+  priority: number
+  error_codes: number[]
+  keywords: string[]
+  match_mode: 'any' | 'all'
+  platforms: string[]
+  passthrough_code: boolean
+  response_code: number | null
+  passthrough_body: boolean
+  custom_message: string | null
+  description: string | null
+  created_at: string
+  updated_at: string
+}
+
+/**
+ * Create rule request
+ */
+export interface CreateRuleRequest {
+  name: string
+  enabled?: boolean
+  priority?: number
+  error_codes?: number[]
+  keywords?: string[]
+  match_mode?: 'any' | 'all'
+  platforms?: string[]
+  passthrough_code?: boolean
+  response_code?: number | null
+  passthrough_body?: boolean
+  custom_message?: string | null
+  description?: string | null
+}
+
+/**
+ * Update rule request
+ */
+export interface UpdateRuleRequest {
+  name?: string
+  enabled?: boolean
+  priority?: number
+  error_codes?: number[]
+  keywords?: string[]
+  match_mode?: 'any' | 'all'
+  platforms?: string[]
+  passthrough_code?: boolean
+  response_code?: number | null
+  passthrough_body?: boolean
+  custom_message?: string | null
+  description?: string | null
+}
+
+/**
+ * List all error passthrough rules
+ * @returns List of all rules sorted by priority
+ */
+export async function list(): Promise<ErrorPassthroughRule[]> {
+  const { data } = await apiClient.get<ErrorPassthroughRule[]>('/admin/error-passthrough-rules')
+  return data
+}
+
+/**
+ * Get rule by ID
+ * @param id - Rule ID
+ * @returns Rule details
+ */
+export async function getById(id: number): Promise<ErrorPassthroughRule> {
+  const { data } = await apiClient.get<ErrorPassthroughRule>(`/admin/error-passthrough-rules/${id}`)
+  return data
+}
+
+/**
+ * Create new rule
+ * @param ruleData - Rule data
+ * @returns Created rule
+ */
+export async function create(ruleData: CreateRuleRequest): Promise<ErrorPassthroughRule> {
+  const { data } = await apiClient.post<ErrorPassthroughRule>('/admin/error-passthrough-rules', ruleData)
+  return data
+}
+
+/**
+ * Update rule
+ * @param id - Rule ID
+ * @param updates - Fields to update
+ * @returns Updated rule
+ */
+export async function update(id: number, updates: UpdateRuleRequest): Promise<ErrorPassthroughRule> {
+  const { data } = await apiClient.put<ErrorPassthroughRule>(`/admin/error-passthrough-rules/${id}`, updates)
+  return data
+}
+
+/**
+ * Delete rule
+ * @param id - Rule ID
+ * @returns Success confirmation
+ */
+export async function deleteRule(id: number): Promise<{ message: string }> {
+  const { data } = await apiClient.delete<{ message: string }>(`/admin/error-passthrough-rules/${id}`)
+  return data
+}
+
+/**
+ * Toggle rule enabled status
+ * @param id - Rule ID
+ * @param enabled - New enabled status
+ * @returns Updated rule
+ */
+export async function toggleEnabled(id: number, enabled: boolean): Promise<ErrorPassthroughRule> {
+  return update(id, { enabled })
+}
+
+export const errorPassthroughAPI = {
+  list,
+  getById,
+  create,
+  update,
+  delete: deleteRule,
+  toggleEnabled
+}
+
+export default errorPassthroughAPI

frontend/src/api/admin/index.ts

@@ -19,6 +19,7 @@ import geminiAPI from './gemini'
 import antigravityAPI from './antigravity'
 import userAttributesAPI from './userAttributes'
 import opsAPI from './ops'
+import errorPassthroughAPI from './errorPassthrough'
 
 /**
  * Unified admin API object for convenient access
@@ -39,7 +40,8 @@ export const adminAPI = {
   gemini: geminiAPI,
   antigravity: antigravityAPI,
   userAttributes: userAttributesAPI,
-  ops: opsAPI
+  ops: opsAPI,
+  errorPassthrough: errorPassthroughAPI
 }
 
 export {
@@ -58,10 +60,12 @@ export {
   geminiAPI,
   antigravityAPI,
   userAttributesAPI,
-  opsAPI
+  opsAPI,
+  errorPassthroughAPI
 }
 
 export default adminAPI
 
 // Re-export types used by components
 export type { BalanceHistoryItem } from './users'
+export type { ErrorPassthroughRule, CreateRuleRequest, UpdateRuleRequest } from './errorPassthrough'