Compiler: CALL_PRIM only for real primitives, GLOBAL_GET+CALL for runtime fns

compile-quasiquote, compile-defcomp, compile-defmacro were hardcoding
CALL_PRIM for runtime functions (qq-expand-runtime, eval-defcomp,
eval-defmacro) that aren't in the primitives table. Changed to
GLOBAL_GET + CALL so the VM resolves them from env.bindings at runtime.

The compile-call function already checks (primitive? name) before
emitting CALL_PRIM — only the three special-case compilers were wrong.

Also: register scope-push!/pop! as primitives, add scope-peek/emit!
to OCaml transpiler name mapping, fix sx_runtime.ml scope wrappers
to route through prim_call "scope-push!" etc.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hosts/ocaml/bin/sx_server.ml

@@ -435,6 +435,17 @@ let make_server_env () =
        | [], _ -> Nil)
     | _ -> Nil);
 
+  (* qq-expand-runtime — quasiquote expansion at runtime.
+     The bytecode compiler emits CALL_PRIM "qq-expand-runtime" for
+     backtick expressions. Expands the template with the calling env. *)
+  bind "qq-expand-runtime" (fun args ->
+    match args with
+    | [template] ->
+      (* qq_expand needs an env — use the kernel env *)
+      Sx_ref.qq_expand template (Env env)
+    | [template; Env e] -> Sx_ref.qq_expand template (Env e)
+    | _ -> Nil);
+
   (* Evaluator bridge — aser calls these spec functions.
      Route to the OCaml CEK machine. *)
   bind "eval-expr" (fun args ->