feat(multiplayer): persist ranked arena allocations

server/domain/ranked.go

@@ -11,7 +11,8 @@ type RankedParticipant struct {
 }
 
 type RankedArena struct {
-	ID string
+	ID   string
+	Path string
 }
 
 // rankedArenas is the server-owned eligibility registry for launch ranked
@@ -19,9 +20,9 @@ type RankedArena struct {
 // project, but deliberately excludes every elevated-goal variant until a
 // policy trained for that geometry is promoted.
 var rankedArenas = map[string]RankedArena{
-	"arena_01": {ID: "arena_01"},
-	"arena_02": {ID: "arena_02"},
-	"arena_03": {ID: "arena_03"},
+	"arena_01": {ID: "arena_01", Path: "res://scenes/arena_01.tscn"},
+	"arena_02": {ID: "arena_02", Path: "res://scenes/arena_02.tscn"},
+	"arena_03": {ID: "arena_03", Path: "res://scenes/arena_03.tscn"},
 }
 
 // DefaultRankedArena supplies a safe server-owned eligibility decision while