chore: update bin scripts — rename references from .sh to plain names

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

bin/arty

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-# arty.sh - A bash library repository and release management system
+# arty - A bash library repository management system
 # Version: 1.0.0
 
 set -euo pipefail