优化 local 模式兼容性与部署可靠性

- SQL 方言层：agent updated_at、dashboard 小时分桶、清理任务跨 SQLite/MySQL
- Cache Capabilities：redka 跳过 ZSet/PubSub，Agent 聚合改 DB 直读
- local 模式 redka 初始化失败 Fatal；/version 返回 features
- SQLite WAL + 连接池限制；K8s data 改 PVC 持久化
- run.sh：旧参数迁移、升级后 /version 校验

backend/pkg/database/dialect.go

@@ -0,0 +1,43 @@
+package database
+
+import (
+	"strings"
+
+	"gorm.io/gorm"
+)
+
+// DriverName 从 GORM 连接获取驱动名（sqlite / mysql / postgres）// Logan.Li
+func DriverName(db *gorm.DB) string {
+	if db == nil || db.Dialector == nil {
+		return "mysql"
+	}
+	name := strings.ToLower(db.Dialector.Name())
+	switch {
+	case strings.Contains(name, "sqlite"):
+		return "sqlite"
+	case strings.Contains(name, "postgres"):
+		return "postgres"
+	default:
+		return "mysql"
+	}
+}
+
+// HourBucketExpr 按小时分桶表达式（跨 SQLite / MySQL）// Logan.Li
+func HourBucketExpr(driver string) string {
+	switch driver {
+	case "sqlite":
+		return "cast(strftime('%s', report_time) as integer) / 3600"
+	default:
+		return "UNIX_TIMESTAMP(report_time) DIV 3600"
+	}
+}
+
+// CleanupAgentReportsSQL 清理 7 天前 Agent 上报 // Logan.Li
+func CleanupAgentReportsSQL(driver string) string {
+	switch driver {
+	case "sqlite":
+		return "DELETE FROM monitor_agent_reports WHERE report_time < datetime('now', '-7 days')"
+	default:
+		return "DELETE FROM monitor_agent_reports WHERE report_time < DATE_SUB(NOW(), INTERVAL 7 DAY)"
+	}
+}