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>

qml/CatMoods.qml

@@ -0,0 +1,13 @@
+pragma Singleton
+import QtQuick
+import TNCat
+
+// Maps CatController::Mood onto the strings Cat.qml understands.
+QtObject {
+    readonly property var names: ["walking", "running", "sitting", "grooming", "stretching",
+                                  "sleeping", "loving", "alert", "chasing", "batting"]
+
+    function name(mood) {
+        return names[mood] !== undefined ? names[mood] : "sitting"
+    }
+}