chore: initial padel scaffold + design docs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

source/garmin-padelDelegate.mc

@@ -0,0 +1,15 @@
+import Toybox.Lang;
+import Toybox.WatchUi;
+
+class garmin_padelDelegate extends WatchUi.BehaviorDelegate {
+
+    function initialize() {
+        BehaviorDelegate.initialize();
+    }
+
+    function onMenu() as Boolean {
+        WatchUi.pushView(new Rez.Menus.MainMenu(), new garmin_padelMenuDelegate(), WatchUi.SLIDE_UP);
+        return true;
+    }
+
+}