Add WebSocket support for switch status updates

- Define `LoadSwStatus` protobuf message for switch state data (`main` and `usb`).
- Introduce `updateSwitchStatusUI` to synchronize UI with WebSocket switch status payloads.
- Update backend logic to manage and broadcast switch status changes dynamically.

Signed-off-by: YoungSoo Shin <shinys000114@gmail.com>

page/src/ui.js

@@ -61,6 +61,21 @@ export function updateUptimeUI(uptimeInSeconds) {
     }
 }
 
+/**
+ * Updates the power switch toggle states based on WebSocket data.
+ * @param {Object} swStatus - The switch status object from the WebSocket message.
+ */
+export function updateSwitchStatusUI(swStatus) {
+    if (swStatus) {
+        if (swStatus.main !== undefined) {
+            dom.mainPowerToggle.checked = swStatus.main;
+        }
+        if (swStatus.usb !== undefined) {
+            dom.usbPowerToggle.checked = swStatus.usb;
+        }
+    }
+}
+
 /**
  * Updates the Wi-Fi status indicator in the header.
  * @param {Object} data - The Wi-Fi status object from the WebSocket.