fix: 恢复腾讯云账单同步并完善成本预测

- 接入腾讯云单日账单、全局限频和指数退避

- 修正月末费用预测并增加账期提示和费用归因

- 补充腾讯云限频及账单归因回归测试

frontend/src/locales/en-US.json

@@ -8795,6 +8795,19 @@
     "costPredict.recRising": "Cost trending up, monitor new service spending",
     "costPredict.recDeclining": "Cost declining, optimization is effective",
     "costPredict.recStable": "Cost stable, maintain current strategy"
+    ,"costPredict.incompletePeriod": "The current billing period is incomplete. Data is available through {{date}} and the forecast will change as billing continues"
+    ,"costPredict.incompletePrompt": "- Billing note: current period is incomplete; data through {{date}}"
+    ,"costPredict.costAttribution": "Cost Change Attribution"
+    ,"costPredict.baselinePeriod": "Baseline"
+    ,"costPredict.comparisonPeriod": "Comparison"
+    ,"costPredict.costChange": "Cost change"
+    ,"costPredict.sectionAttribution": "[Cost Change Attribution]"
+    ,"costPredict.noAttribution": "No comparable cost change attribution is available"
+    ,"costPredict.attributionLine": "- {{dimension}} / {{name}}: change {{delta}} CNY, contribution {{contribution}}%"
+    ,"costPredict.dimension.provider": "Provider"
+    ,"costPredict.dimension.account_name": "Account"
+    ,"costPredict.dimension.service": "Service"
+    ,"costPredict.dimension.region": "Region"
   },
   "breadcrumb": {
     "aiAlertAnalyzer": "Alert Analysis",

frontend/src/locales/zh-CN.json

@@ -8795,6 +8795,19 @@
     "costPredict.recRising": "费用呈上升趋势，建议关注新增服务消费",
     "costPredict.recDeclining": "费用持续下降，成本优化有效",
     "costPredict.recStable": "费用平稳，保持当前成本策略"
+    ,"costPredict.incompletePeriod": "当前账期尚未结束，费用数据截至 {{date}}，预测结果会随出账继续变化"
+    ,"costPredict.incompletePrompt": "- 账期说明：当前账期未结束，数据截至 {{date}}"
+    ,"costPredict.costAttribution": "费用变化归因"
+    ,"costPredict.baselinePeriod": "基准期"
+    ,"costPredict.comparisonPeriod": "对比期"
+    ,"costPredict.costChange": "费用变化"
+    ,"costPredict.sectionAttribution": "【费用变化归因】"
+    ,"costPredict.noAttribution": "暂无可归因的同期费用变化"
+    ,"costPredict.attributionLine": "- {{dimension}} / {{name}}：变化 {{delta}} 元，贡献 {{contribution}}%"
+    ,"costPredict.dimension.provider": "云厂商"
+    ,"costPredict.dimension.account_name": "账号"
+    ,"costPredict.dimension.service": "服务"
+    ,"costPredict.dimension.region": "区域"
   },
   "breadcrumb": {
     "aiAlertAnalyzer": "告警分析",