Plexamp Lite 1.13: read ahead the next two tracks, keep loaded roots

Read-ahead keeps the next two tracks on the SD card (one without it) and drops files
that are no longer coming up. Trusted roots are cached once read, and a failed read
is retried instead of leaving every server untrusted until a restart.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

AndroidManifest.xml

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.minamp"
-    android:versionCode="13"
-    android:versionName="1.12"
+    android:versionCode="14"
+    android:versionName="1.13"
     android:installLocation="internalOnly">
 
     <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="10" />