Adds an in-person 2-player (pass-and-play) mode, selectable from a new
1P/2P toggle at the top of the New Game screen. Selecting 2 Players
hides Move Suggestions, Difficulty Level, and Player Color (none apply
when both sides are human), including in the in-game pause menu. The
board uses a fixed orientation (White bottom, Black top, no flipping)
and reuses the existing PlayerParticipant turn-gating for both sides.

This required migrating the whole app off the private com.mudita
kompakt-ui artifact (and the private Sentry/AboutLibraries plugins and
Nexus repo) onto the publicly published com.mudita:MMD library, since
the private dependency made the project unbuildable outside Mudita's
own infrastructure. Renamed the app to "Chess+" with its own
applicationId so it installs alongside the stock Chess app without
conflict. Verified end to end with a real build, full test suite, and
on-device testing on a Mudita Kompakt, which also surfaced and fixed a
color scheme inversion, invisible button contrast, and a missing
material-icons-core runtime dependency.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>