ocaml: phase 1+3 record type declarations (+3 tests, 447 total)

type r = { x : int; mutable y : string } parses to
(:type-def-record NAME PARAMS FIELDS) with FIELDS each (NAME) or
(:mutable NAME). Parser dispatches on { after = to parse field list.
Field-type sources are skipped (HM registration TBD). Runtime no-op
since records already work as dynamic dicts.

lib/ocaml/test.sh

@@ -1098,6 +1098,14 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 3901)
 (eval "(ocaml-run-program \"let x = 10 ;; let _ = x ;; x * 2\")")
 
+;; ── Record type declarations ──────────────────────────────────
+(epoch 4000)
+(eval "(ocaml-parse-program \"type point = { x : int; y : int }\")")
+(epoch 4001)
+(eval "(ocaml-parse-program \"type r = { mutable x : int; y : string }\")")
+(epoch 4002)
+(eval "(ocaml-run-program \"type point = { x : int; y : int };; let p = { x = 3; y = 4 };; p.x + p.y\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 180 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1738,6 +1746,11 @@ check 3802 "let-mut f and g"              '"Int"'
 check 3900 "let _ = 1+2;; 42"             '42'
 check 3901 "two top-level lets, _"        '20'
 
+# ── Record type declarations ──────────────────────────────────
+check 4000 "record type decl"             '("type-def-record" "point" () (("x") ("y")))'
+check 4001 "mutable field decl"           '("mutable" "x")'
+check 4002 "record decl + use"            '7'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"