fix: add é and ë to Ukrainian layout

[marvinctl]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

• Added é and ë to the long-press popup for the Ukrainian Cyrillic е key.
• Ordered the popup as éе4ë, keeping ordinary е centred whether the number row is enabled or hidden.
• Updated the changelog.

Tests performed

• xmllint --noout app/src/main/res/xml/keys_letters_ukrainian.xml
• ./gradlew :app:processCoreDebugResources --no-daemon

Related issue

• Refs Error of the Ukrainian keyboard layout #487

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• I understand every change in this pull request.

[arhivarius13]

Hi! Thanks for working on this.
Just to clarify regarding #487: I meant the Cyrillic letter ё (U+0451), not the Latin letters é or ë.
The issue is that I cannot type ё from the Ukrainian keyboard layout. Could you please check whether ё should also be added to the е long-press popup?
For example, I would expect long-pressing е to offer ё.
Thanks!