chore(release): bump version, update changelog

app/build.gradle.kts

@@ -1,8 +1,18 @@
 /*
  * Copyright (c) 2025 Nishant Mishra
  *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ * This file is part of Tomato - a minimalist pomodoro timer for Android.
+ *
+ * Tomato is free software: you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License as published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tomato is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tomato.
+ * If not, see <https://www.gnu.org/licenses/>.
  */
 
 import org.gradle.api.tasks.testing.logging.TestExceptionFormat
@@ -33,8 +43,8 @@ android {
         applicationId = "org.nsh07.pomodoro"
         minSdk = 27
         targetSdk = 36
-        versionCode = 14
-        versionName = "1.6.0-alpha01"
+        versionCode = 15
+        versionName = "1.6.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }