Update device app icons

[kentonralphtoews]

Checklist

• App update process has been followed
• Target branch is develop
• Application version has been bumped

Adds updated device app icons and deleted old icons

[kentonralphtoews]

Hi! I've updated the PR to match the app-boilerplate structure:
Changes made:

✅ Moved all icon files to /app/icons/ directory
✅ Updated Makefile to use modern Makefile.standard_app structure (matching the boilerplate)
✅ Icon files properly referenced:

Nano X/S+ → icons/Nano Icon 16px.png
Stax → icons/32px Ledger Stax.png
Flex → icons/40px Ledger Flex.png
Apex P → icons/32px Ledger Stax.png

The workflows are currently waiting for maintainer approval to run. Could someone please approve the workflows so the CI can run and turn green?

Yes, I'm using Claude. I appreciate your patience.

Thank you

[kentonralphtoews]

I think I just realized I'm making this way more difficult for myself. Going to close this and start all over again. I'm just going to change the filenames of my images to match the current filenames and upload those in a new PR.