Rename to TNCat, add chip chase, G-codes and a Wayland layout

The project is now TNCat, after HEIDENHAIN's TNC controls. Binary, QML module
URI, settings path, bundle id and .desktop entry follow; the environment
switches are TNCAT_*.

Entertainment: a curled steel chip skitters in every minute or two, the cat
runs it down and bats it away a few times before sitting back looking pleased.
Mood changes flash the matching machine code above its head, G00 for a sprint,
G01 for a stroll, M08 while it washes, G28 for a stretch, M30 for a nap.

Window handling was split into two layouts. X11 and macOS keep one small window
per object, positioned by the app. Wayland gets a screen-filling overlay whose
input region is masked down to the cat, since a Wayland client cannot place its
own window. Overlay mode is automatic there and available elsewhere via
TNCAT_OVERLAY=1.

Also adds a ground-line setting so the cat can walk above a softkey row.

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

src/main.cpp

@@ -1,7 +1,6 @@
 #include <QApplication>
 #include <QQmlApplicationEngine>
 #include <QQuickStyle>
-#include <QQuickWindow>
 #include <QLoggingCategory>
 
 #include "appsettings.h"
@@ -10,9 +9,8 @@
 
 int main(int argc, char *argv[])
 {
-    QCoreApplication::setOrganizationName("workcat");
-    QCoreApplication::setOrganizationDomain("workcat.app");
-    QCoreApplication::setApplicationName("Workcat");
+    QCoreApplication::setOrganizationName("TNCat");
+    QCoreApplication::setApplicationName("TNCat");
     QApplication::setQuitOnLastWindowClosed(false);
 
     // QApplication (not QGuiApplication) so QSystemTrayIcon can show a menu.
@@ -24,7 +22,7 @@ int main(int argc, char *argv[])
     TrayController tray(&cat);
 
     if (QGuiApplication::platformName().startsWith(QLatin1String("wayland"))) {
-        qWarning("Workcat: Wayland does not let a client place its own window. "
+        qWarning("TNCat: Wayland does not let a client place its own window. "
                  "Run with QT_QPA_PLATFORM=xcb for the cat to walk.");
     }
 
@@ -35,10 +33,9 @@ int main(int argc, char *argv[])
     });
     QObject::connect(&engine, &QQmlApplicationEngine::objectCreationFailed, &app,
                      [] { QCoreApplication::exit(1); }, Qt::QueuedConnection);
-    engine.loadFromModule("Workcat", "Main");
+    engine.loadFromModule("TNCat", "Main");
 
-    if (auto *root = qobject_cast<QQuickWindow *>(engine.rootObjects().value(0))) {
-        cat.setWindow(root);
+    if (QObject *root = engine.rootObjects().value(0)) {
         QObject::connect(&tray, &TrayController::settingsRequested, root,
                          [root] { QMetaObject::invokeMethod(root, "openSettings"); });
     }