Add advantage/disadvantage rolling for initiative

Right-click or long-press the d20 button (per-combatant or Roll All)
to open a context menu with Advantage and Disadvantage options.
Normal left-click behavior is unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/hooks/use-long-press.ts

@@ -0,0 +1,32 @@
+import { useCallback, useRef } from "react";
+
+const LONG_PRESS_MS = 500;
+
+export function useLongPress(onLongPress: (e: React.TouchEvent) => void) {
+	const timerRef = useRef<ReturnType<typeof setTimeout>>(undefined);
+	const firedRef = useRef(false);
+
+	const onTouchStart = useCallback(
+		(e: React.TouchEvent) => {
+			firedRef.current = false;
+			timerRef.current = setTimeout(() => {
+				firedRef.current = true;
+				onLongPress(e);
+			}, LONG_PRESS_MS);
+		},
+		[onLongPress],
+	);
+
+	const onTouchEnd = useCallback((e: React.TouchEvent) => {
+		clearTimeout(timerRef.current);
+		if (firedRef.current) {
+			e.preventDefault();
+		}
+	}, []);
+
+	const onTouchMove = useCallback(() => {
+		clearTimeout(timerRef.current);
+	}, []);
+
+	return { onTouchStart, onTouchEnd, onTouchMove };
+}