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/src/main/java/com/streamplayer/StreamChannel.java

@@ -0,0 +1,19 @@
+package com.streamplayer;
+
+public class StreamChannel {
+    private final String name;
+    private final String pageUrl;
+
+    public StreamChannel(String name, String pageUrl) {
+        this.name = name;
+        this.pageUrl = pageUrl;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getPageUrl() {
+        return pageUrl;
+    }
+}