fix: remove duplicate ESC handlers causing double history.back()

AboutModal, ProfileModal, and ShareDialog each had their own
useEscapeKey hook AND were handled by the global ESC handler in
App.tsx. When ESC was pressed, both fired synchronously, calling
history.back() twice — navigating past the current page instead
of just closing the modal.

Removed the per-modal useEscapeKey calls since the global handler
in App.tsx already manages ESC priority for all modals.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/components/AboutModal.tsx

@@ -1,7 +1,6 @@
 import { useEffect, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { FRONTEND_VERSION, GITHUB_URL } from "../App";
-import { useEscapeKey } from "../hooks/useEscapeKey";
 
 interface UpdateCheckResult {
 	status: "up-to-date" | "update-available" | "error";
@@ -18,7 +17,7 @@ export default function AboutModal({ isOpen, onClose }: AboutModalProps) {
 	const [isChecking, setIsChecking] = useState(false);
 	const [updateCheckResult, setUpdateCheckResult] = useState<UpdateCheckResult | null>(null);
 
-	useEscapeKey(isOpen, onClose);
+	// ESC is handled by the global handler in App.tsx to avoid double history.back()
 
 	// Reset check result when modal opens so stale results are never shown
 	useEffect(() => {