Test 32-bit platforms in CI

## What problem does this solve or what need does it fill?

We don't currently test 32-bit platforms in CI, despite advertising best-effort support for things like GameBoy Advance.

See #21401 for a bug that should have been caught automatically, but was instead shipped.

## What solution would you like?

Run basic tests for a 32-bit no_std target in CI.

## What alternative(s) have you considered?

We could probably run this weekly and be fine. Breakage here is rare.

Start by inspecting the repository's existing CI workflows and basic test commands, then identify the 32-bit no_std target needed for the advertised GameBoy Advance support. Done means CI runs the basic tests on that target and catches the class of failure described in #21401, with weekly execution considered if appropriate.

Written by the indexing model from the issue text.