more scalable output;

--- a/src/Pure/Isar/calculation.ML	Thu Apr 24 14:23:36 2025 +0200
+++ b/src/Pure/Isar/calculation.ML	Thu Apr 24 20:42:04 2025 +0200
@@ -160,7 +160,7 @@
       if int then
         Proof_Context.pretty_fact ctxt'
           (Proof_Context.full_name ctxt' (Binding.name calculationN), calc)
-        |> Pretty.string_of |> writeln
+        |> Pretty.writeln
       else ();
   in state' |> final ? (update_calculation NONE #> Proof.chain_facts calc) end;