fix(client): explicit Variant type on JSON.parse_string return

GDScript strict mode rejects type inference from Variant-returning
functions. JSON.parse_string() returns Variant — use explicit type
annotation to satisfy the parser.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/rendering/character_visual.gd

@@ -475,7 +475,7 @@ func _read_coverage(path: String) -> Dictionary:
 	var file := FileAccess.open(path, FileAccess.READ)
 	if file == null:
 		return {}
-	var parsed := JSON.parse_string(file.get_as_text())
+	var parsed: Variant = JSON.parse_string(file.get_as_text())
 	file.close()
 	if parsed is Dictionary:
 		return parsed