perf: 全栈查询优化、前端缓存去重与页面可见性优化

后端:
- SQL count 查询统一改用 func.count() 子查询替代 query.count()
- Dashboard/Audit 等页面多次独立查询合并为单次聚合查询
- Provider summary 列表改为批量查询消除 N+1 问题
- DailyStats 逐天循环查询改为 CASE 分桶单次查询
- 使用 load_only() 减少不必要的列加载
- cache_decorator 支持嵌套属性路径解析(dotted vary_by)
- 多个管理/公共端点新增 @cache_result 缓存装饰

前端:
- cache.ts 新增 in-flight 请求复用、dedupedRequest、buildCacheKey
- 大量 API 调用添加前端缓存或去重
- 多个页面定时器在标签页隐藏时暂停、可见时恢复
- Auth 检查从 setInterval 改为 storage + visibilitychange 事件驱动
- 请求竞态防护(requestId 模式)

数据库:
- Usage 表新增 idx_usage_status_user_created 复合索引

frontend/src/views/admin/system-settings/composables/useSystemConfig.ts

@@ -111,7 +111,7 @@ function createDefaultConfig(): SystemConfig {
     // 请求记录清理
     enable_auto_cleanup: true,
     detail_log_retention_days: 7,
-    compressed_log_retention_days: 90,
+    compressed_log_retention_days: 30,
     header_retention_days: 90,
     log_retention_days: 365,
     cleanup_batch_size: 1000,
@@ -179,7 +179,7 @@ export function useSystemConfig() {
       systemConfig.value.max_request_body_size !== originalConfig.value.max_request_body_size ||
       systemConfig.value.max_response_body_size !== originalConfig.value.max_response_body_size ||
       JSON.stringify(systemConfig.value.sensitive_headers) !==
-        JSON.stringify(originalConfig.value.sensitive_headers)
+      JSON.stringify(originalConfig.value.sensitive_headers)
     )
   })
 
@@ -187,14 +187,14 @@ export function useSystemConfig() {
     if (!originalConfig.value) return false
     return (
       systemConfig.value.detail_log_retention_days !==
-        originalConfig.value.detail_log_retention_days ||
+      originalConfig.value.detail_log_retention_days ||
       systemConfig.value.compressed_log_retention_days !==
-        originalConfig.value.compressed_log_retention_days ||
+      originalConfig.value.compressed_log_retention_days ||
       systemConfig.value.header_retention_days !== originalConfig.value.header_retention_days ||
       systemConfig.value.log_retention_days !== originalConfig.value.log_retention_days ||
       systemConfig.value.cleanup_batch_size !== originalConfig.value.cleanup_batch_size ||
       systemConfig.value.audit_log_retention_days !==
-        originalConfig.value.audit_log_retention_days
+      originalConfig.value.audit_log_retention_days
     )
   })
 
@@ -231,7 +231,7 @@ export function useSystemConfig() {
         try {
           const response = await adminApi.getSystemConfig(key)
           if (response.value !== null && response.value !== undefined) {
-            ;(systemConfig.value as Record<string, unknown>)[key] = response.value
+            ; (systemConfig.value as Record<string, unknown>)[key] = response.value
           }
         } catch {
           // 配置不存在时使用默认值，无需处理