Co-op campaign "League against the Lightwatch": 20 missions, selectable on the Match page

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/it.lang

@@ -1330,6 +1330,7 @@ demo.m2.start = Una mappa casuale. Nemmeno io l'avevo mai vista.
 demo.m2.wave = Sono passati due minuti: arrivano gli eroi.
 net.coop_editor = Editor campaign
 net.coop_builtin = Built-in campaign
+net.coop_league = Lega contro la Guardia della Luce
 net.coop_editor_mission = Editor campaign {0}: mission {1} ({2})
 net.coop_editor_none = No mission of the editor campaign fits co-op (map at least 72x72, a goal besides rival masters)
 blk.until = Ripeti finché