Update source code with grid layout and channel management

Major changes:
- Add ChannelAdapter for grid display functionality
- Add ChannelRepository for data management
- Add PlayerActivity for dedicated video playback
- Add StreamChannel model for channel representation
- Update MainActivity to support grid layout
- Update activity_main.xml with grid UI components
- Add channel item layouts and drawables
- Update AndroidManifest.xml with new activity
- Update build.gradle dependencies

This implements the requested "grilla arreglada" functionality with proper channel grid display and management.

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

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

app/build.gradle

@@ -40,6 +40,7 @@ dependencies {
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation 'androidx.appcompat:appcompat:1.6.1'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
+    implementation 'androidx.recyclerview:recyclerview:1.3.2'
 
     // ExoPlayer para reproducción de video
     implementation 'com.google.android.exoplayer:exoplayer:2.18.7'