Add list tools; normalize tool names and paths in transcript

internal/dirlist/dirlist.go

@@ -0,0 +1,34 @@
+package dirlist
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const keep = 64<<10 - 100
+
+func List(path string) (string, error) {
+	entries, err := os.ReadDir(path)
+	if err != nil {
+		return "", err
+	}
+	if len(entries) == 0 {
+		return fmt.Sprintf("%s is empty.\n", path), nil
+	}
+	b := &strings.Builder{}
+	for i, e := range entries {
+		name := e.Name()
+		info, err := os.Stat(filepath.Join(path, name))
+		if err == nil && info.IsDir() {
+			name += "/"
+		}
+		if b.Len()+len(name)+1 > keep {
+			fmt.Fprintf(b, "(%d more entries not shown; output stops at 64 KiB)\n", len(entries)-i)
+			break
+		}
+		b.WriteString(name + "\n")
+	}
+	return b.String(), nil
+}