pulls/pr_01m3xsjpehe75by7vy5ma74jt2

Commit

Handle empty and whitespace-only names, trim whitespace from input

When a name is empty or contains only whitespace, greet 'world' instead of printing "Hello, !" or including the whitespace. Also trim leading/trailing whitespace from valid names. Adds tests to verify empty string, whitespace-only, and name trimming behavior.