feat(widget): Add theme customization to widget configuration

Add color presets, custom color picker, transparency slider, and device
label toggle to the widget configuration screen. Widget preview updates
in real-time. Use profile label as device name in both preview and
actual widget.

app/src/main/res/drawable/ic_baseline_check_24.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M9,16.17L4.83,12l-1.42,1.41L9,19 21,7l-1.41,-1.41z" />
+</vector>

app/src/main/res/drawable/widget_color_swatch_bg.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="oval">
+    <solid android:color="#FFFFFF" />
+    <stroke
+        android:width="1dp"
+        android:color="#20000000" />
+</shape>

app/src/main/res/drawable/widget_color_swatch_selected_ring.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="oval">
+    <stroke
+        android:width="3dp"
+        android:color="?colorPrimary" />
+</shape>

app/src/main/res/drawable/widget_preview_bg.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <corners android:radius="16dp" />
+    <solid android:color="@android:color/transparent" />
+</shape>

app/src/main/res/drawable/widget_preview_checkerboard.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <corners android:radius="16dp" />
+    <solid android:color="?colorSurfaceVariant" />
+</shape>