fix(files): the token list is fresh after the sessions end, a copy again reads Copied again, the Copied button says so

frontend/src/components/useCopyFeedback.ts

@@ -1,4 +1,4 @@
-import { useState } from "react";
+import { useEffect, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 
 import { copyText } from "../lib/clipboard";
@@ -17,11 +17,15 @@ const COPIED_MS = 2000;
 export function useCopyFeedback(): { copied: boolean; copy: (value: string) => Promise<void> } {
   const { t } = useTranslation();
   const [copied, setCopied] = useState(false);
+  // One reset at a time: a copy again within the moment starts it over, not cut short by the last.
+  const timer = useRef<number | undefined>(undefined);
+  useEffect(() => () => window.clearTimeout(timer.current), []);
   const copy = async (value: string) => {
     if (await copyText(value)) {
       setCopied(true);
       notify({ level: "success", message: t("common.copy.done") });
-      window.setTimeout(() => setCopied(false), COPIED_MS);
+      window.clearTimeout(timer.current);
+      timer.current = window.setTimeout(() => setCopied(false), COPIED_MS);
       return;
     }
     notify({ level: "warning", message: t("common.copy.failed") });