Mörsergranate: explosion radius in the tooltip

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/dwarf-arts.md

@@ -70,3 +70,9 @@ Mod: the construct call notes grenade, owner, landing point and radius
 (`ImpactRadius`, shared with the hit check); after `0x62d530` a disc (alpha
 0x40) with a 2 px rim (alpha 0xa0) is drawn there, without depth test, until
 the impact of that owner's grenade at that point gathers its targets.
+
+Tooltip (2026-10-26, "the skills tooltip does not show the current radius"):
+a game::Art tooltip filter adds "Explosionsradius: N" after the last value
+line of each level section (current level, and the next level's in the skill
+book), in that line's colour, from the same `ImpactRadiusAt(level)` as the
+hit check and the marker.