VM global_env sync + isomorphic nav store primitives

Reverse hook syncs VM GLOBAL_SET mutations back to global_env so CEK reads
see JIT-written values. Isomorphic nav: store primitives, event-bridge,
client? predicate. Browser JS and bytecode rebuilt.

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

hosts/ocaml/lib/sx_vm.ml

@@ -303,7 +303,11 @@ and run vm =
               in find_env env
             | None -> false
           in
-          if not written then Hashtbl.replace vm.globals name (peek vm)
+          if not written then begin
+            let v = peek vm in
+            Hashtbl.replace vm.globals name v;
+            (match !Sx_types._vm_global_set_hook with Some f -> f name v | None -> ())
+          end
 
         (* ---- Control flow ---- *)
         | 32 (* OP_JUMP *) ->