fix: 安全性与代码质量加固（异常保护、外键级联、竞态修复、优雅关机）

src/web/components/TimeRangePicker.tsx

@@ -1,4 +1,5 @@
 import { useState } from "react";
+import { subtractHours } from "../utils/time";
 
 interface TimeRangePickerProps {
   from: string;
@@ -18,12 +19,6 @@ function toLocalDatetimeInput(date: Date): string {
   return `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}T${pad(date.getHours())}:${pad(date.getMinutes())}`;
 }
 
-function subtractHours(date: Date, hours: number): Date {
-  const result = new Date(date);
-  result.setTime(result.getTime() - hours * 60 * 60 * 1000);
-  return result;
-}
-
 export function TimeRangePicker({ from, to, onChange }: TimeRangePickerProps) {
   const [activeShortcut, setActiveShortcut] = useState<string | null>("24h");