ocaml: phase 6 Map.Make / Set.Make functors (+4 tests, 418 total)

Both written in OCaml inside lib/ocaml/runtime.sx:

  module Map = struct module Make (Ord) = struct
    let empty = []
    let add k v m = ... (* sorted insert via Ord.compare *)
    let find_opt / find / mem / remove / bindings / cardinal
  end end

  module Set = struct module Make (Ord) = struct
    let empty = []
    let mem / add / remove / elements / cardinal
  end end

Sorted association list / sorted list backing — linear ops but
correct. Strong substrate-validation: Map.Make is a non-trivial
functor implemented entirely on top of the OCaml-on-SX evaluator.

plans/ocaml-on-sx.md

@@ -286,8 +286,11 @@ SX CEK evaluator (both JS and OCaml hosts)
 - [ ] `Int`/`Float`: arithmetic, `to_string`, `of_string_opt`, `min_int`, `max_int`.
 - [ ] `Hashtbl`: `create`, `add`, `replace`, `find`, `find_opt`, `remove`, `mem`,
       `iter`, `fold`, `length` — backed by SX mutable dict.
-- [ ] `Map.Make` functor — balanced BST backed by SX sorted dict.
-- [ ] `Set.Make` functor.
+- [x] `Map.Make` functor — sorted association list backed
+      (insert/find/remove/mem/cardinal/bindings); not a balanced tree
+      but linear with parametric `Ord` ordering.
+- [x] `Set.Make` functor — sorted list backed
+      (add/mem/remove/elements/cardinal).
 - [ ] `Printf`: `sprintf`, `printf`, `eprintf` — format strings via `(format ...)`.
 - [ ] `Sys`: `argv`, `getenv_opt`, `getcwd` — via `perform` IO.
 - [ ] Scoreboard runner: `lib/ocaml/conformance.sh` + `scoreboard.json`.
@@ -383,6 +386,14 @@ the "mother tongue" closure: OCaml → SX → OCaml. This means:
 
 _Newest first._
 
+- 2026-05-08 Phase 6 — `Map.Make` / `Set.Make` functors written in
+  OCaml (+4 tests, 418 total). Sorted association list / sorted list
+  backed (linear ops, but correct). Both take an `Ord` module supplying
+  `compare`. Tested: `module IntMap = Map.Make(IntOrd) ;; IntMap.find
+  …` and `IntSet.elements (IntSet.add 3 (IntSet.add 1 …))` returning
+  `[1; 2; 3]`. Strong substrate-validation for the functor system —
+  Map.Make is a non-trivial functor implemented entirely on top of the
+  OCaml-on-SX evaluator.
 - 2026-05-08 Phase 6 — `Sys` module constants (+5 tests, 414 total).
   os_type, word_size, max_array_length, max_string_length,
   executable_name, big_endian, unix, win32, cygwin. Constants-only