feat(rate-limit): 实现分层 RPM 限速，支持系统默认/用户/独立Key三级配置

- 新增用户级 rate_limit 字段，支持系统默认/用户自定义/不限制三种模式
- 独立 Key 的 rate_limit 语义调整：null=跟随系统默认，0=不限制，>0=自定义
- 实现 UserRpmLimiter 基于 Redis sliding window 的 RPM 限速引擎
- Pipeline 请求流程集成用户级 RPM 检查
- 管理后台和用户面板新增 RPM 限速配置与实时状态查看
- 系统设置新增全局默认 RPM 配置项
- 迁移脚本回填现有 API Key 的 rate_limit 默认值
- 新增用户/Key RPM 状态监控 API 和前端展示

Closes #231

Co-authored-by: LewisPen <LewisPen@nyadoo.com>

frontend/src/stores/users.ts

@@ -1,6 +1,13 @@
 import { defineStore } from 'pinia'
 import { ref } from 'vue'
-import { usersApi, type User, type CreateUserRequest, type UpdateUserRequest, type ApiKey } from '@/api/users'
+import {
+  usersApi,
+  type User,
+  type CreateUserRequest,
+  type UpdateUserRequest,
+  type ApiKey,
+  type UpsertUserApiKeyRequest
+} from '@/api/users'
 import { parseApiError } from '@/utils/errorParser'
 
 export const useUsersStore = defineStore('users', () => {
@@ -84,15 +91,28 @@ export const useUsersStore = defineStore('users', () => {
     }
   }
 
-  async function createApiKey(userId: string, name?: string): Promise<ApiKey> {
+  async function createApiKey(userId: string, data: UpsertUserApiKeyRequest): Promise<ApiKey> {
     try {
-      return await usersApi.createApiKey(userId, name)
+      return await usersApi.createApiKey(userId, data)
     } catch (err: unknown) {
       error.value = parseApiError(err, '创建 API Key 失败')
       throw err
     }
   }
 
+  async function updateApiKey(
+    userId: string,
+    keyId: string,
+    data: UpsertUserApiKeyRequest
+  ): Promise<ApiKey> {
+    try {
+      return await usersApi.updateApiKey(userId, keyId, data)
+    } catch (err: unknown) {
+      error.value = parseApiError(err, '更新 API Key 失败')
+      throw err
+    }
+  }
+
   async function deleteApiKey(userId: string, keyId: string) {
     try {
       await usersApi.deleteApiKey(userId, keyId)
@@ -121,6 +141,7 @@ export const useUsersStore = defineStore('users', () => {
     deleteUser,
     getUserApiKeys,
     createApiKey,
+    updateApiKey,
     deleteApiKey,
     getFullApiKey
   }