Don't let dead players cap the grid-mode buffer indicator

Strict-intersecting all 10 tiles' buffered ranges meant a player who died
at t=30 capped the unified bar at 30 even when every other tile was
buffered to the round end. Pad each player's buffer with [dur, roundEnd]
before intersecting — there's no stream there for them to buffer, so they
should drop out as a constraint past their own death.

src/lib/components/perspective-grid.svelte

@@ -81,7 +81,22 @@
 	const tileBuffers = new Map<number, BufferedRange[]>();
 
 	function intersectAll(): BufferedRange[] {
-		const lists = Array.from(tileBuffers.values()).filter((ranges) => ranges.length > 0);
+		const roundEnd = Math.max(0, ...Array.from(playerDurations.values()));
+		if (roundEnd <= 0) return [];
+
+		// For a player who died early (stream shorter than the round), pad the
+		// buffer list with a synthetic [dur, roundEnd] range. There is no stream
+		// there for them to buffer, so they shouldn't constrain the unified
+		// indicator past their own death.
+		const lists: BufferedRange[][] = [];
+		for (const [player, ranges] of tileBuffers) {
+			const dur = playerDurations.get(player);
+			const padded =
+				dur != null && Number.isFinite(dur) && dur < roundEnd
+					? [...ranges, { start: dur, end: roundEnd }]
+					: ranges;
+			if (padded.length > 0) lists.push(padded);
+		}
 		if (!lists.length) return [];
 
 		let acc = lists[0];