feat(rpm): RPM 限流模块优化

P0:
- rpm_override 嵌入 Auth Cache Snapshot，消除每请求 DB 查询 (snapshot v6→v7)
- 429 RPM 响应返回 Retry-After 头（当前分钟剩余秒数）

P1:
- ClearAll 按钮直连 DELETE API，带 loading 防重复
- 新增 GET /admin/users/:id/rpm-status 管理员 RPM 用量查询端点

优化:
- checkRPM 从级联互斥改为并行取最严，user.rpm_limit 作为全局硬上限始终生效
- Override/Group 变更后自动失效 auth cache
- fail-open 语义不变，Redis 故障不阻塞业务

frontend/src/i18n/locales/en.ts

@@ -894,6 +894,8 @@ export default {
     description: 'Manage your account information and settings',
     accountBalance: 'Account Balance',
     concurrencyLimit: 'Concurrency Limit',
+    rpmLimit: 'RPM Limit',
+    rpmUnlimited: 'Unlimited',
     memberSince: 'Member Since',
     overviewTitle: 'Account Overview',
     overviewDescription: 'Check account status, profile sources, and common actions at a glance.',
@@ -1490,6 +1492,11 @@ export default {
       copyPassword: 'Copy password',
       creating: 'Creating...',
       updating: 'Updating...',
+      form: {
+        rpmLimit: 'Requests Per Minute (RPM)',
+        rpmLimitPlaceholder: '0 = unlimited',
+        rpmLimitHint: 'Max requests per minute for this user; 0 = unlimited. Acts as a fallback only when the group has no rpm_limit set.'
+      },
       columns: {
         user: 'User',
         id: 'ID',
@@ -1704,6 +1711,10 @@ export default {
         name: 'Name',
         platform: 'Platform',
         rateMultiplier: 'Rate Multiplier',
+        rpmOverride: 'RPM Override',
+        rpmOverrideHint: 'Per-user RPM cap in this group; empty = group default; 0 = unlimited',
+        rateDefault: 'default',
+        rpmDefault: 'default',
         type: 'Type',
         accounts: 'Accounts',
         capacity: 'Capacity',
@@ -1730,7 +1741,10 @@ export default {
         platform: 'Platform',
         rateMultiplier: 'Rate Multiplier',
         status: 'Status',
-        exclusive: 'Exclusive Group'
+        exclusive: 'Exclusive Group',
+        rpmLimit: 'Requests Per Minute (RPM)',
+        rpmLimitPlaceholder: '0 = unlimited',
+        rpmLimitHint: 'Max requests per minute for each user in this group; 0 = unlimited. Once set, it takes over per-user rate limiting in this group (overrides the user-level rpm_limit fallback).'
       },
       enterGroupName: 'Enter group name',
       optionalDescription: 'Optional description',
@@ -1762,6 +1776,12 @@ export default {
       rateMultipliers: 'Rate Multipliers',
       rateMultipliersTitle: 'Group Rate Multipliers',
       addUserRate: 'Add User Rate Multiplier',
+      rpmOverrides: 'RPM Overrides',
+      rpmOverridesTitle: 'Group RPM Overrides',
+      addUserRpm: 'Add User RPM Override',
+      noRpmOverrides: 'No users have an RPM override yet',
+      rpmSaved: 'RPM overrides saved',
+      groupRpmDefault: 'Group default RPM',
       searchUserPlaceholder: 'Search user email...',
       noRateMultipliers: 'No user rate multipliers configured',
       rateUpdated: 'Rate multiplier updated',
@@ -4503,6 +4523,8 @@ export default {
         defaultBalanceHint: 'Initial balance for new users',
         defaultConcurrency: 'Default Concurrency',
         defaultConcurrencyHint: 'Maximum concurrent requests for new users',
+        defaultUserRpmLimit: 'Default User RPM Limit',
+        defaultUserRpmLimitHint: 'Default max requests per minute for new users; 0 = unlimited. Only applied at new user creation.',
         defaultSubscriptions: 'Default Subscriptions',
         defaultSubscriptionsHint: 'Auto-assign these subscriptions when a new user is created or registered',
         addDefaultSubscription: 'Add Default Subscription',

frontend/src/i18n/locales/zh.ts

@@ -898,6 +898,8 @@ export default {
     description: '管理您的账户信息和设置',
     accountBalance: '账户余额',
     concurrencyLimit: '并发限制',
+    rpmLimit: 'RPM 限制',
+    rpmUnlimited: '不限制',
     memberSince: '注册时间',
     overviewTitle: '账户总览',
     overviewDescription: '快速查看账号状态、资料来源与常用设置。',
@@ -1589,7 +1591,10 @@ export default {
         balanceLabel: '余额',
         concurrencyLabel: '并发数',
         statusLabel: '状态',
-        selectStatus: '选择状态'
+        selectStatus: '选择状态',
+        rpmLimit: '每分钟请求数 (RPM)',
+        rpmLimitPlaceholder: '0 表示不限制',
+        rpmLimitHint: '该用户每分钟最大请求数，0 = 不限制；仅在所用分组未设置 rpm_limit 时作为兜底生效'
       },
       adjustBalance: '调整余额',
       adjustConcurrency: '调整并发数',
@@ -1756,6 +1761,10 @@ export default {
         name: '名称',
         platform: '平台',
         rateMultiplier: '费率倍数',
+        rpmOverride: 'RPM 覆盖',
+        rpmOverrideHint: '该用户在此分组的 RPM 上限；留空 = 使用分组默认；0 = 不限制',
+        rateDefault: '默认',
+        rpmDefault: '默认',
         exclusive: '独占',
         type: '类型',
         priority: '优先级',
@@ -1790,6 +1799,9 @@ export default {
         descriptionPlaceholder: '请输入描述（可选）',
         rateMultiplierLabel: '费率倍数',
         rateMultiplierHint: '1.0 = 标准费率，0.5 = 半价，2.0 = 双倍',
+        rpmLimit: '每分钟请求数 (RPM)',
+        rpmLimitPlaceholder: '0 表示不限制',
+        rpmLimitHint: '每用户在本分组每分钟最大请求数，0 = 不限制；一旦设置即接管该用户的限流（覆盖用户级 rpm_limit）',
         exclusiveLabel: '专属分组',
         exclusiveHint: '专属分组，可以手动指定给用户',
         platformLabel: '平台限制',
@@ -1859,6 +1871,12 @@ export default {
       rateMultipliers: '专属倍率',
       rateMultipliersTitle: '分组专属倍率管理',
       addUserRate: '添加用户专属倍率',
+      rpmOverrides: '专属 RPM',
+      rpmOverridesTitle: '分组专属 RPM 管理',
+      addUserRpm: '添加用户专属 RPM',
+      noRpmOverrides: '暂无用户设置了专属 RPM',
+      rpmSaved: '专属 RPM 已保存',
+      groupRpmDefault: '分组默认 RPM',
       searchUserPlaceholder: '搜索用户邮箱...',
       noRateMultipliers: '暂无用户设置了专属倍率',
       rateUpdated: '专属倍率已更新',
@@ -4668,6 +4686,8 @@ export default {
         defaultBalanceHint: '新用户的初始余额',
         defaultConcurrency: '默认并发数',
         defaultConcurrencyHint: '新用户的最大并发请求数',
+        defaultUserRpmLimit: '默认用户 RPM 限制',
+        defaultUserRpmLimitHint: '新用户默认每分钟最大请求数，0 = 不限制；仅作用于新用户创建时初始化',
         defaultSubscriptions: '默认订阅列表',
         defaultSubscriptionsHint: '新用户创建或注册时自动分配这些订阅',
         addDefaultSubscription: '添加默认订阅',