Head unit is 1920x720, not 1920x1080

FIRMWARE.md, the mise emulator profile and SPECS.md said 1920x1080.
The MG4's display is 1920x720 at 160 dpi (an app window has been seen
at 1778x720, the car's sidebar taking the rest). The floating button's
geometry test now uses 1920x720.

The app itself assumed no height: checked on an Android 9 emulator at
1920x720, all tabs render (longer ones scroll), the sidebar holds all
seven tabs, and the floating button starts at 1840,312.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QLJfZQZeAKAwSqViTmLzki

app/src/test/java/com/evsuite/abrp/FloatingButtonGeometryTest.java

@@ -12,8 +12,8 @@ public class FloatingButtonGeometryTest {
 
     @Test
     public void startsAtTheRightEdgeAboutFortyPercentDown() {
-        // 1920 x 1080 head unit, 64 px button, 16 px margin.
-        assertArrayEquals(new int[]{1840, 432}, FloatingButtonGeometry.defaultPosition(1920, 1080, 64, 16));
+        // The MG4 head unit is 1920 x 720; 64 px button, 16 px margin.
+        assertArrayEquals(new int[]{1840, 288}, FloatingButtonGeometry.defaultPosition(1920, 720, 64, 16));
     }
 
     @Test