ocaml: phase 5.1 baseline 8/8 — quicksort + exceptions + closures

Added 3 baseline programs:
- closures.ml — curried make_adder; verifies closure capture
- quicksort.ml — recursive sort using List.filter + List.append, sums result
- exception_handle.ml — exception NegArg of int + raise + try/with

All 8/8 baseline programs pass through ocaml-run-program. Combined the
suite exercises: let-rec, modules, refs, for-loops, pattern matching,
exceptions, lambdas, list ops (map/filter/append/fold), arithmetic.

run.sh streamlined to one sx_server invocation per program. End-to-end
runtime ≈2 min.

lib/ocaml/baseline/expected.json

@@ -1,7 +1,10 @@
 {
+  "closures.ml": 315,
+  "exception_handle.ml": 4,
   "factorial.ml": 3628800,
   "list_ops.ml": 30,
-  "option_match.ml": 5,
   "module_use.ml": 3,
+  "option_match.ml": 5,
+  "quicksort.ml": 44,
   "sum_squares.ml": 385
 }