feat(i18n): cloud 模块全量国际化迁移 — 4 组件 + 90 新增翻译键

迁移组件:
- RegionManager.tsx — providerNames→getProviderNames(t) 函数模式, 全量 t() 替换
- CloudAccountManager.tsx — providerLabels→getProviderLabels(t), 卡片/弹框/表单全量迁移
- CloudBilling.tsx — 概览/记录/预警三 Tab 全量迁移, TrendChart/StatStrip 标签国际化
- DomainManager.tsx — 域名卡片/状态徽章/创建编辑弹框全量迁移

翻译键: cloud 命名空间 145→235 键 (+90), common 新增 deleteFailed/deleteSuccess
验证: tsc -b=0, npm build✅ (21.21s), 17/17 集成测试通过, 0 缺失键, 0 残留 UI 中文

frontend/src/locales/en-US.json

@@ -471,7 +471,9 @@
     "channel": "Channel",
     "contact": "Contact",
     "true": "Yes",
-    "false": "No"
+    "false": "No",
+    "deleteFailed": "Delete failed",
+    "deleteSuccess": "Deleted successfully"
   },
   "menu": {
     "dashboard": "Dashboard",
@@ -3822,7 +3824,95 @@
     "setBudget": "Set Budget",
     "budgetAlert": "Budget Alert",
     "budgetUsage": "Budget Usage",
-    "budgetRemaining": "Budget Remaining"
+    "budgetRemaining": "Budget Remaining",
+    "code": "Code",
+    "vendor": "Vendor",
+    "location": "Location",
+    "enabled": "Enabled",
+    "disabled": "Disabled",
+    "allVendors": "All Vendors",
+    "selectedRegionCount": "{{count}} regions selected",
+    "clearSelection": "Clear Selection",
+    "batchDelete": "Batch Delete",
+    "batchDeleteRegion": "Batch Delete Regions",
+    "batchDeleteRegionConfirm": "Are you sure you want to delete the selected {{count}} regions? This action cannot be undone.",
+    "batchDeletedRegions": "{{count}} regions deleted",
+    "batchDeleteFailed": "Batch delete failed",
+    "deleteRegionConfirm": "Are you sure you want to delete \"{{name}}\"? This action cannot be undone.",
+    "regionDeleted": "Region deleted",
+    "regionsSubtitle": "Manage cloud provider regions and endpoints",
+    "noRegionData": "No region data",
+    "searchRegion": "Search region name or code...",
+    "noMatchRegion": "No matching regions",
+    "geoLocation": "Geographic Location",
+    "regionNamePlaceholder": "e.g. North China-Beijing",
+    "regionCodePlaceholder": "e.g. cn-north-1",
+    "locationPlaceholder": "e.g. Beijing, China",
+    "endpointPlaceholder": "e.g. ecs.cn-north-1.aliyuncs.com",
+    "normal": "Normal",
+    "stopped": "Stopped",
+    "error": "Error",
+    "searchAccount": "Search account name or AccessKey...",
+    "accountsSubtitle": "Manage multi-cloud access credentials and account info",
+    "noAccountData": "No cloud account data",
+    "monthlyFee": "Monthly Fee",
+    "serverCount": "Servers",
+    "keepBlank": "Leave blank to keep unchanged",
+    "monthlyFeeUnit": "Monthly Fee (CNY)",
+    "saveChanges": "Save Changes",
+    "createAccount": "Create Account",
+    "editAccountDesc": "Modify account info and credentials. Leave blank to keep existing.",
+    "addAccountDesc": "Enter multi-cloud credentials for resource sync and cost tracking",
+    "accountNamePlaceholder": "e.g. Aliyun Production",
+    "platformLabel": "Cloud Platform",
+    "allPlatforms": "All Platforms",
+    "loadStatsFailed": "Failed to load statistics",
+    "loadBillingFailed": "Failed to load billing",
+    "loadAlertRulesFailed": "Failed to load alert rules",
+    "deleteBillingConfirm": "Are you sure you want to delete this cost record?",
+    "operationFailed": "Operation failed",
+    "overviewStats": "Overview",
+    "costRecords": "Cost Records",
+    "startDate": "Start Date",
+    "endDate": "End Date",
+    "query": "Query",
+    "billingSubtitle": "Multi-cloud cost statistics, records and alerts",
+    "today": "Today",
+    "thisMonth": "This Month",
+    "yearly": "Yearly",
+    "alertCount": "{{count}} alerts",
+    "recordCost": "Record Cost",
+    "costAlert": "Cost Alerts",
+    "monthlyAccumulated": "Monthly Accumulated",
+    "current": "Current",
+    "monthVendorDistribution": "Monthly Vendor Cost Distribution",
+    "noDistributionData": "No distribution data",
+    "noStatsData": "No statistics data",
+    "noCostRecords": "No cost records",
+    "colDate": "Date",
+    "colService": "Service",
+    "colRegion": "Region",
+    "colAccount": "Account",
+    "colCost": "Cost",
+    "colDescription": "Description",
+    "noAlertRules": "No alert rules",
+    "alertRuleHint": "Add rules to manage cost threshold alerts",
+    "colMetric": "Metric",
+    "lastTriggered": "Last Triggered",
+    "deleteBillingRecord": "Delete Billing Record",
+    "deleteAlertRule": "Delete Alert Rule",
+    "deleteAlertRuleConfirm": "Are you sure you want to delete this alert rule?",
+    "pending": "Pending",
+    "searchDomain": "Search domains...",
+    "allStatus": "All Status",
+    "domainsSubtitle": "Manage domain registration and DNS records",
+    "noDomainData": "No domain data",
+    "recordCountLabel": "DNS Record Count",
+    "enableSsl": "Enable SSL",
+    "createDomain": "Create Domain",
+    "editDomainDesc": "Modify domain registration, DNS config and SSL certificate status",
+    "addDomainDesc": "Enter domain info including registrar, DNS provider and expiry date",
+    "daysLeft": "{{count}} days"
   },
   "agent": {
     "title": "Agent Management",