Improve the search function to include "é", "è" as a search for "e" and vice versa

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App version

6.400

Where did you get the app from?

F-Droid

Android version

LineageOS 18.1 / Android 11

Device model

Samsung Galaxy S5 / Samsung Galaxy S7

Steps to reproduce

In one empty folder, put an email with a word containing a "é" in the Subjet, like "école".

Now search this folder with "ecole".

Expected behavior

The email with "école" in the subject is found.

The same change permit a search with "a" for "à", etc.

Actual behavior

No email is found.

Logs

No response

Start with the app's search function and reproduce the issue in an empty folder using an email whose subject contains “école”; compare searches for “ecole” and “école”. No implementation files or tests are named, so first identify the search entry point and its existing test coverage. Done means accented and unaccented equivalents match, including examples such as “a” and “à”.