chore: untrack IDE and OS junk files from git

Remove .DS_Store (macOS) and .idea/ (IntelliJ) from tracking.
Both are now listed in .gitignore to prevent re-committing.

Author: Yuval

.DS_Store

@@ -47,6 +47,7 @@ Thumbs.db
 
 # IDE
 .vs/
+.idea/
 *.user
 *.suo