fix(android): visible D-pad focus stroke on setup buttons (#218)

The setup screen buttons used a bare <ripple> which only reacts to
state_pressed (touch). D-pad navigation triggers state_focused, which the
ripple ignored, leaving the focused button nearly invisible against the
dark background from TV viewing distance.

Wrap the button shape in a <selector> (kept inside the ripple so touch
still gets the press ripple) that adds a bright 3dp white stroke on
state_focused.

Closes #209

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

android/app/src/main/res/drawable/button_primary.xml

@@ -1,10 +1,26 @@
 <?xml version="1.0" encoding="utf-8"?>
+<!--
+  Keeps the touch press ripple, and adds a high-contrast white stroke on
+  state_focused so D-pad navigation on Android TV is visible from across the
+  room (the bare <ripple> only reacted to state_pressed). See issue #209.
+-->
 <ripple xmlns:android="http://schemas.android.com/apk/res/android"
     android:color="#2563EB">
     <item>
-        <shape android:shape="rectangle">
+        <selector>
-            <solid android:color="#3B82F6" />
+            <item android:state_focused="true">
-            <corners android:radius="8dp" />
+                <shape android:shape="rectangle">
-        </shape>
+                    <solid android:color="#3B82F6" />
+                    <stroke android:width="3dp" android:color="#FFFFFF" />
+                    <corners android:radius="8dp" />
+                </shape>
+            </item>
+            <item>
+                <shape android:shape="rectangle">
+                    <solid android:color="#3B82F6" />
+                    <corners android:radius="8dp" />
+                </shape>
+            </item>
+        </selector>
     </item>
 </ripple>