refactor(ota): implement polling-based update system and fix API typo

- Fix typo in OTA update status API endpoint (/ota_udpate_status → /ota_update_status)
- Replace WebSocket-based update progress with polling mechanism
- Add OTA lifecycle callbacks (started, finished, progress, error)
- Implement check_update_task with internet connectivity verification
- Add LittleFS/SPIFFS update support
- Simplify update progress page to use 90-second delay and polling instead of real-time WebSocket updates

This refactor improves reliability by checking internet connectivity before attempting updates and simplifies the frontend by removing WebSocket complexity in favor of a timeout-based polling approach.

data/logic.js

@@ -49,7 +49,7 @@ function fetchWaterData(gauge) {
 }
 
 function fetchUpdateData(gauge) {
-    const apiUrl = '/ota_udpate_status';
+    const apiUrl = '/ota_update_status';
     // Fetching data from the API
     fetch(apiUrl)
         .then(response => response.json())