Bump version to 1.3 (versionCode 3)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: markrcote

app/build.gradle.kts

@@ -12,8 +12,8 @@ android {
         applicationId = "com.markrcote.gvtimer"
         minSdk = 24
         targetSdk = 36
-        versionCode = 2
-        versionName = "1.2"
+        versionCode = 3
+        versionName = "1.3"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }