Minamp 1.6: adjustable UI size, larger text and controls

- New setting "Text and button size" (Normal / Large / Extra large): scales
  text, icons and buttons on top of the phone's density (App.UI_SCALES)
- Larger default text, rows, tiles, touch targets and player icons; all sizes
  now live in res/values/dimens.xml
- Seek bar knob drawn in code, since Android 2.x caches XML shapes at the
  size they were first loaded
- Full-width buttons wrap to two lines instead of cutting words off
- Shorter labels so they fit 240x320 screens in both languages
- tools/check_fit.py checks that UI texts fit their slots at every size and
  language using Droid Sans metrics; build.sh runs it and setup_toolchain.sh
  fetches the font

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

res/layout/activity_home.xml

@@ -9,7 +9,7 @@
     <LinearLayout
         android:id="@+id/tabs"
         android:layout_width="match_parent"
-        android:layout_height="32dp"
+        android:layout_height="@dimen/tabs"
         android:orientation="horizontal">
         <TextView android:id="@+id/tab_home" style="@style/Tab" android:text="@string/tab_home" />
         <TextView android:id="@+id/tab_artists" style="@style/Tab" android:text="@string/tab_artists" />
@@ -20,7 +20,7 @@
     <View
         android:id="@+id/tab_line"
         android:layout_width="80dp"
-        android:layout_height="2dp"
+        android:layout_height="3dp"
         android:background="@color/accent" />
 
     <FrameLayout