feat: improve accessibility, security & user interaction in notifications and setup

- Replaced `div` with `button` elements in `NotificationHandler` for better semantics and accessibility.
- Added conditional QR Code reveal in 2FA setup with `blur` effect for enhanced security and user control.
- Enhanced messages layout for responsiveness on smaller screens with dynamic chat/sidebar toggling.
- Simplified legacy prop handling in `ShareDialog`.

frontend/src/components/share-dialog.tsx

@@ -28,9 +28,10 @@ interface ShareDialogProps {
 export function ShareDialog({
 	contentId,
 	contentTitle,
+	contentUrl: _unused, // Support legacy prop
 	open,
 	onOpenChange,
-}: Omit<ShareDialogProps, "contentUrl">) {
+}: ShareDialogProps) {
 	const [searchQuery, setSearchQuery] = React.useState("");
 	const [results, setResults] = React.useState<User[]>([]);
 	const [isLoading, setIsLoading] = React.useState(false);