fix(chat): support body and content fields in world and DM chat messages; feat(audio): add sound toggle switch and mute controls

scripts/smoke_test_chat_ui.gd

@@ -58,6 +58,14 @@ func _run() -> void:
 	}
 	ui._add_message_row(ui.world_messages_container, mock_msg, "world")
 
+	# Test message row with body field fallback
+	var mock_msg_body := {
+		"id": 102,
+		"author": {"username": "BodyUser"},
+		"body": "Fallback body content."
+	}
+	ui._add_message_row(ui.world_messages_container, mock_msg_body, "world")
+
 	if ui.world_messages_container.get_child_count() == 0:
 		printerr("FAIL: Message row was not added to world_messages_container")
 		quit(1)
@@ -75,6 +83,14 @@ func _run() -> void:
 		quit(1)
 		return
 
+	var row2: HBoxContainer = ui.world_messages_container.get_child(1)
+	var lbl2: Label = row2.get_child(0) as Label
+	if not lbl2 or not lbl2.text.contains("Fallback body content."):
+		printerr("FAIL: Fallback body text was not displayed in message row")
+		quit(1)
+		return
+	print("PASS: Message row with body fallback verified.")
+
 	print("PASS: Message row with Report button verified.")
 
 	# Test report dialog preparation