ADFA-4886: restyle the collapsed-bar handle as a Material 3 tab

Make the recovery handle read as the nav bar's own surface peeking from the bottom
edge instead of a separate button: a colorSurfaceContainer tab with rounded top
corners and 8dp elevation (matching the bar), carrying a drag grabber tinted
colorOnSurfaceVariant. Drops the now-unused ic_expand_less.

Author: luisguzman-adfa

controller/app/src/main/res/drawable/bg_nav_handle.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- ADFA-4886: the collapsed-bar handle reads as the nav bar's own surface peeking from the
+     bottom edge — same colorSurfaceContainer as the bar, rounded top corners only. -->
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <solid android:color="?attr/colorSurfaceContainer" />
+    <corners
+        android:topLeftRadius="14dp"
+        android:topRightRadius="14dp"
+        android:bottomLeftRadius="0dp"
+        android:bottomRightRadius="0dp" />
+</shape>

controller/app/src/main/res/drawable/ic_expand_less.xml

@@ -0,0 +1,7 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="32dp" android:height="24dp"
+    android:viewportWidth="32" android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+    <path android:fillColor="#FF000000"
+        android:pathData="M8,10h16a2,2 0 0 1 0,4h-16a2,2 0 0 1 0,-4z"/>
+</vector>

controller/app/src/main/res/drawable/ic_nav_grabber.xml

@@ -14,19 +14,21 @@
 
     <!-- ADFA-4886: nav chrome uses Material 3 vector icons + theme attributes (system day/night)
          instead of emoji/glyph text buttons. Icon-only buttons carry a contentDescription. -->
+    <!-- Collapsed-bar handle: a Material 3 tab of the bar's own surface with a drag grabber,
+         so it reads as the nav bar peeking from the bottom edge rather than a separate button. -->
     <ImageButton
         android:id="@+id/btnHandle"
-        android:layout_width="60dp"
-        android:layout_height="32dp"
+        android:layout_width="56dp"
+        android:layout_height="24dp"
         android:layout_alignParentBottom="true"
         android:layout_centerHorizontal="true"
-        android:alpha="0.8"
-        android:background="?attr/colorSurfaceContainerHighest"
+        android:background="@drawable/bg_nav_handle"
         android:contentDescription="@string/k2go_nav_show_bar"
-        android:padding="4dp"
-        android:scaleType="fitCenter"
+        android:elevation="8dp"
+        android:padding="0dp"
+        android:scaleType="center"
         android:tint="?attr/colorOnSurfaceVariant"
-        app:srcCompat="@drawable/ic_expand_less" />
+        app:srcCompat="@drawable/ic_nav_grabber" />
 
     <LinearLayout
         android:id="@+id/bottomNav"