Player grid: gate skull on availability, not on round-final survival

The skull icon was shown whenever the POV's chunks-preview row had
survived_chunk=false — i.e. for any player who died at any point in the
round. But that summary doesn't move with playback time, so at the start
of a round non-survivors got a skull while still being alive on video
and with their button still enabled. Now the skull only fires once the
player has actually died by the current virtualTime (mirroring grid-tile
which already did this). Survivors still get the shield.

src/lib/components/player-grid.svelte

@@ -102,7 +102,7 @@
 		</div>
 		{#if p.survived}
 			<ShieldIcon size={14} weight="duotone" class="text-emerald-500" />
-		{:else}
+		{:else if !available}
 			<SkullIcon size={14} weight="duotone" class="text-rose-500" />
 		{/if}
 	</ToggleGroup.Item>