WATranslate UI Fix v2.2

Purpose:
Stops the active conversation from visibly reloading every 5 seconds.

Upload/extract directly into:
public_html/whatsapp-server-translator/

Overwrite existing files.

Files replaced:
- assets/app.js
- public/assets/app.js
- public/index.php

Changes:
- Keeps 5-second polling for new messages.
- Does NOT redraw contacts unless their data changed.
- Does NOT redraw the active conversation unless message data changed.
- Background polling no longer shows "Loading conversation…".
- Preserves scroll position when background updates occur.
- A newly arriving message still appears automatically.

After extraction:
Hard refresh Firefox with Cmd + Shift + R.

Verification:
Open:
https://alldevlabs.com/whatsapp-server-translator/assets/app.js?v=2.2

Bottom line should contain:
console.log("WATranslate UI JS version 2.2 loaded");
