ocaml: phase 5 HM tuple + list types (+7 tests, 326 total)

Tuple type (hm-con "*" TYPES); list type (hm-con "list" (TYPE)).
ocaml-infer-tuple threads substitution through each item left-to-right.
ocaml-infer-list unifies all items with a fresh 'a (giving 'a list for
empty []).

Pretty-printer renders 'Int * Int' for tuples and 'Int list' for lists,
matching standard OCaml notation.

Examples:
  fun x y -> (x, y) : 'a -> 'b -> 'a * 'b
  fun x -> [x; x] : 'a -> 'a list
  []                : 'a list

lib/ocaml/test.sh

@@ -798,6 +798,22 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 1422)
 (eval "(ocaml-run \"Result.map_error (fun e -> e + 1) (Error 5)\")")
 
+;; ── HM extensions: tuples + lists ──────────────────────────────
+(epoch 1500)
+(eval "(ocaml-type-of \"(1, 2)\")")
+(epoch 1501)
+(eval "(ocaml-type-of \"(1, true, \\\"hi\\\")\")")
+(epoch 1502)
+(eval "(ocaml-type-of \"[1; 2; 3]\")")
+(epoch 1503)
+(eval "(ocaml-type-of \"[]\")")
+(epoch 1504)
+(eval "(ocaml-type-of \"fun x -> [x; x]\")")
+(epoch 1505)
+(eval "(ocaml-type-of \"fun x y -> (x, y)\")")
+(epoch 1506)
+(eval "(ocaml-type-of \"[true; false]\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 180 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1263,6 +1279,15 @@ check 1420 "Result.get_ok"                '42'
 check 1421 "Result.to_option Ok"          '("Some" 1)'
 check 1422 "Result.map_error"             '("Error" 6)'
 
+# ── HM tuples + lists ───────────────────────────────────────────
+check 1500 "type tuple Int*Int"           '"Int * Int"'
+check 1501 "type 3-tuple"                 '"Int * Bool * String"'
+check 1502 "type Int list"                '"Int list"'
+check 1503 "type [] poly"                 ' list'
+check 1504 "type fn -> list"              'list"'
+check 1505 "type fn -> tuple"             ' * '
+check 1506 "type Bool list"               '"Bool list"'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"