JIT: use live globals, don't copy — fixes CSSX Not callable: nil

jit_compile_lambda now uses the live globals table directly instead
of Hashtbl.copy. Closure bindings that aren't already in globals are
injected into the live table. This ensures GLOBAL_GET always sees
the latest define values.

Previously: Hashtbl.copy created a stale snapshot. Functions defined
after the copy (like cssx-process-token from cssx.sx) resolved to nil
in JIT-compiled closures.

JIT error test now passes — 0 CSSX errors during navigation.
7/8 navigation tests pass. Remaining: back button content update.

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

hosts/ocaml/lib/sx_vm.ml

@@ -580,23 +580,27 @@ let jit_compile_lambda (l : lambda) globals =
        so the VM can find them via GLOBAL_GET. The compiler doesn't know
        about the enclosing scope, so closure vars get compiled as globals. *)
     let effective_globals =
+      (* Use the LIVE globals table directly. Inject only truly local
+         closure bindings (not already in globals) into the live table.
+         This ensures GLOBAL_GET always sees the latest define values.
+         Previous approach copied globals, creating a stale snapshot. *)
       let closure = l.l_closure in
-      if Hashtbl.length closure.bindings = 0 && closure.parent = None then
-        globals  (* no closure vars — use globals directly *)
-      else begin
-        (* Merge: closure bindings layered on top of globals.
-           Use a shallow copy so we don't pollute the real globals. *)
-        let merged = Hashtbl.copy globals in
-        let rec inject env =
-          Hashtbl.iter (fun id v -> Hashtbl.replace merged (Sx_types.unintern id) v) env.bindings;
-          match env.parent with Some p -> inject p | None -> ()
-        in
+      let count = ref 0 in
+      let rec inject env =
+        Hashtbl.iter (fun id v ->
+          let name = Sx_types.unintern id in
+          if not (Hashtbl.mem globals name) then begin
+            Hashtbl.replace globals name v;
+            incr count
+          end
+        ) env.bindings;
+        match env.parent with Some p -> inject p | None -> ()
+      in
+      if Hashtbl.length closure.bindings > 0 || closure.parent <> None then
         inject closure;
-        let n = Hashtbl.length merged - Hashtbl.length globals in
-        if n > 0 then
-          Printf.eprintf "[jit] %s: injected %d closure bindings\n%!" fn_name n;
-        merged
-      end
+      if !count > 0 then
+        Printf.eprintf "[jit] %s: injected %d closure bindings\n%!" fn_name !count;
+      globals
     in
     (match result with
     | Dict d when Hashtbl.mem d "bytecode" ->