add ElegantOTA and fix LittleFS boot mount

[Yukti007]

Links

• Closes Firmware, factoryTest, Add ElegantOTA and LittleFS #379

What & Why

• LittleFS was already in the code but only activated during test A. Moved mount to setup() so it is ready at boot — ElegantOTA requires it to be available immediately on startup.
• ElegantOTA was completely missing from the codebase. Added the three required libraries (AsyncTCP, ESPAsyncWebServer, ElegantOTA) and set up a web server instance.
• Added startOTAServerIfNeeded() helper that starts the OTA server automatically once Wi-Fi is up, triggered at the end of both Wi-Fi AP (test 7) and Wi-Fi STA (test 8).
• Added new test entry E (ElegantOTA) for operator browser verification, consistent with the existing test pattern.
• Added ElegantOTA.loop() to loop() to keep OTA file transfers running.

Validation / How to Verify

1. Flash the updated firmware onto the board.
2. Install the three required libraries via Arduino Library Manager: AsyncTCP, ESPAsyncWebServer, ElegantOTA.
3. Open Serial Monitor at 115200 baud and confirm LittleFS mounted OK appears on boot.
4. Run test 7 (Wi-Fi AP) or test 8 (Wi-Fi STA) and confirm ElegantOTA server started appears in the serial output.
5. Run test E and open http://<IP>/update in a browser — confirm the ElegantOTA upload page loads and mark PASS.
6. Run P (Run All) and confirm test E appears in the summary with a result.

Checklist

• Only related changes : FactoryTest_wMenu.ino
• Folder structure respected, work directory : Firmware/factoryTest/FactoryTest_wMenu/FactoryTest_wMenu.ino