fix(cmd/edit): implement removal of "last modified" comments

The removeLastModifiedComments function previously copied all lines without filtering.
This change adds logic to remove lines containing "last modified" (case-insensitive)
after trimming whitespace.

cmd/edit.go

@@ -103,7 +103,11 @@ var editCmd = &cobra.Command{
 func removeLastModifiedComments(content string) string {
 	lines := strings.Split(content, "\n")
 	cleanedLines := make([]string, 0, len(lines))
-	cleanedLines = append(cleanedLines, lines...)
-
+	for _, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		if !strings.Contains(strings.ToLower(trimmed), "last modified") {
+			cleanedLines = append(cleanedLines, line)
+		}
+	}
 	return strings.Join(cleanedLines, "\n")
-}
+}