Git: Add .kotlin directory to .gitignore

Ignore the .kotlin directory which contains temporary
kotlin compiler session files that should not be tracked.

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

Author: ParaskP7

.gitignore

@@ -41,6 +41,9 @@ proguard/
 gradle.properties
 !/benchmark/gradle.properties
 
+# Kotlin compiler sessions
+.kotlin/
+
 # OS X generated file
 .DS_Store