Add alphabetical sorting for Android TV channel list

Alphabetical Sorting Features:
- ChannelRepository updated with alphabetical sorting
- ChannelAdapter optimized for sorted display
- Channel focus and selection improvements
- Added arrays.xml for channel categories and sorting
- Enhanced UI components for TV navigation

Code Changes:
- ChannelRepository: addSortChannels() method
- ChannelAdapter: optimized for alphabetical display
- AndroidManifest.xml: updated for sorting features
- item_channel.xml: improved focus states
- bg_channel_item_selector.xml: enhanced visual feedback

TV Navigation Improvements:
- Consistent alphabetical order (A-Z)
- Better focus management for D-Pad navigation
- Enhanced visual indicators for selected channels
- Improved readability on large screens
- Quick channel location with remote control

This improves the Android TV user experience by making channel discovery faster and more intuitive.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

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

@@ -1,30 +1,39 @@
 <?xml version="1.0" encoding="utf-8"?>
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_selected="true">
+        <shape android:shape="rectangle">
+            <solid android:color="#88003C8F" />
+            <corners android:radius="18dp" />
+            <stroke
+                android:width="3dp"
+                android:color="#FFFFFFFF" />
+        </shape>
+    </item>
     <item android:state_focused="true">
         <shape android:shape="rectangle">
-            <solid android:color="#66FFFFFF" />
-            <corners android:radius="16dp" />
+            <solid android:color="#55003C8F" />
+            <corners android:radius="18dp" />
             <stroke
-                android:width="2dp"
+                android:width="3dp"
                 android:color="#FFFFFFFF" />
         </shape>
     </item>
     <item android:state_pressed="true">
         <shape android:shape="rectangle">
-            <solid android:color="#55FFFFFF" />
-            <corners android:radius="16dp" />
+            <solid android:color="#55003C8F" />
+            <corners android:radius="18dp" />
             <stroke
-                android:width="2dp"
+                android:width="3dp"
                 android:color="#FFFFFFFF" />
         </shape>
     </item>
     <item>
         <shape android:shape="rectangle">
             <solid android:color="#33212121" />
-            <corners android:radius="16dp" />
+            <corners android:radius="18dp" />
             <stroke
-                android:width="1dp"
-                android:color="#55FFFFFF" />
+                android:width="2dp"
+                android:color="#33FFFFFF" />
         </shape>
     </item>
 </selector>