docs/dev/core-model.md: per-file measured differences between the
Windows, KDE and macOS container, monitor, workspace, window and
window_manager (stripped code lines, changed lines, identical lines),
the platform-specific fields and methods of each layer, a proposed
split into a komorebi-core crate generic over a Platform (Backend plus a
Copy-or-Clone Window and a state type) with the exact order of layers
(container, monitor, workspace, window_manager, router), what the KDE
stack of wip-u-kfde already did, what Windows must do before the crate
can be created, and the list of KDE process_command arms over 20 lines
with the method each became. Measurements are from diff of the files at
this tip; nothing was run on Windows or macOS.
Verified: not applicable (documentation); the numbers were produced by
diff and wc on the files at wip-u-kfde.
