Updated .gitignore

The `.gitignore` file has been reorganized and expanded to include standard exclusions for build artifacts, Kotlin/Java project files, Android Studio metadata, keys/secrets, and OS-generated files.

.gitignore

@@ -1,13 +1,36 @@
+# Build artifacts
+bin/
+gen/
+out/
+build/
+app/build/
+
+# Kotlin / Java
 *.iml
-.gradle
+*.ipr
-/local.properties
+*.iws
-/.idea
+.idea/
-.DS_Store
+.gradle/
-/build
-/captures
-.externalNativeBuild
-.cxx
 local.properties
-/app/build
+
-/.jks
+# Android Studio
-/app/release
+captures/
+.externalNativeBuild/
+.cxx/
+.navigation/
+
+# Keys & Secrets
+*.jks
+*.keystore
+*.p12
+google-services.json
+
+# OS generated files
+.DS_Store
+Thumbs.db
+
+# Log files
+*.log
+
+# Bundle/Release
+/app/release/