feat(ui): add custom theme color support and share app functionality

Introduce a new custom theme feature that allows users to personalize the application background color using RGB sliders, hex input, or a set of predefined palettes.

Key changes include:
* **Custom Theme Engine**: Added `CustomThemeFragment` and `ThemeHelper` to manage color selection and application. The UI dynamically updates the background color across the `MainActivity` and `PlayerFragment` when preferences change.
* **Android TV Support**: Provided a specialized layout for television devices (`fragment_custom_theme.xml` in `layout-television`) with optimized focus handling for D-pad navigation.
* **Share Feature**: Implemented a "Share App" preference in `SettingsFragment` that triggers a standard Android share intent and displays a thank-you notification upon use.
* **Localization**: Added Ukrainian language support and updated string resources for multiple locales (DE, DA, EL, FR, JA, NL, PL, RU) to include the new theme and share options.
* **Persistence**: Updated `PreferencesHelper` and `Keys` to store theme-related settings, including the enabled state, selected color, and predefined color index.

app/src/main/res/navigation/nav_graph_main.xml

@@ -32,6 +32,9 @@
         <action
             android:id="@+id/action_settings_to_visualizer"
             app:destination="@id/visualizer_destination" />
+        <action
+            android:id="@+id/action_settings_to_cstheme"
+            app:destination="@id/custom_theme_destination" />
     </fragment>
 
     <!-- EQUALIZER -->
@@ -52,4 +55,11 @@
         android:name="com.michatec.radio.AddStationFragment"
         android:label="Add Station"
         tools:layout="@layout/dialog_find_station" />
+
+    <!-- CUSTOM THEME -->
+    <fragment
+        android:id="@+id/custom_theme_destination"
+        android:name="com.michatec.radio.CustomThemeFragment"
+        android:label="Custom Theme"
+        tools:layout="@layout/fragment_custom_theme" />
 </navigation>