Add script to get fresh set of shells.

mise.toml

@@ -184,6 +184,10 @@ done
 rmdir "$backups" 2>/dev/null || true
 '''
 
+[tasks.fresh-shells]
+description = "Replace every herdr-core shell playpen keeps with a fresh one, keeping the layout"
+run = "tools/fresh-shells.sh"
+
 [tasks.install]
 description = "Install playpen into ~/.local with a desktop entry and icon"
 depends = ["build"]