v3: modals stop shifting the page — scroll lock moves to <html> and holds the scrollbar's gutter only while locked (and only if a bar was showing), shared by Modal and ConfirmModal with stacked-lock counting; scrollbars take a theme-tinted thumb, inner scrollers go thin and contain their overscroll

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/components/ConfirmModal.tsx

@@ -2,6 +2,7 @@ import { useEffect } from "react";
 import { createPortal } from "react-dom";
 import { t } from "@lingui/core/macro";
 import { Trans } from "@lingui/react/macro";
+import { useScrollLock } from "../hooks/useScrollLock";
 
 interface ConfirmModalProps {
   message: string;
@@ -14,6 +15,7 @@ export function ConfirmModal(
   { message, confirmLabel, onConfirm, onCancel }: ConfirmModalProps,
 ) {
   const label = confirmLabel ?? t`Delete`;
+  useScrollLock();
 
   useEffect(() => {
     const onKey = (e: KeyboardEvent) => {