Add v9.0: Auto-update system with Gitea integration

- Implement UpdateManager to check Gitea releases for new versions
- Add update dialogs with mandatory/optional update support
- Integrate DownloadManager for APK downloads
- Add FileProvider configuration for app installation
- Support update-manifest.json for version control enforcement
- Add comprehensive update strings and error handling
- Include gradlew executable permissions

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

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

release/update-manifest.example.json

@@ -0,0 +1,10 @@
+{
+  "versionCode": 90000,
+  "versionName": "9.0.0",
+  "minSupportedVersionCode": 80000,
+  "forceUpdate": false,
+  "downloadUrl": "https://gitea.cbcren.online/renato97/app/releases/download/v9.0/StreamPlayer-v9.0-DefinitiveEdition.apk",
+  "fileName": "StreamPlayer-v9.0-DefinitiveEdition.apk",
+  "sizeBytes": 12000000,
+  "notes": "Texto opcional si necesitas personalizar las notas que verá el usuario"
+}