compiler(0.R): a dispatched action's record is the queue's to keep - one list per action, filled in place, all free again when the drain ends

dispatch lowered to ludic_act_push(k, new A { ... }): a fresh record every dispatch, and an input
system dispatches Move and FrameTime every frame. The queue now keeps a list per action
(kept<k>, used<k>); ludic_act_new__A hands out the next (made only when all are queued), new's
emitter fills it field by field as it fills a fresh one (every field, default or given), and
drain_actions sets every used<k> back to 0 once the queue is empty. A reducer only ever reads
its action during the drain, so nothing sees a record after it is reused. Actions are visible
to the program's file, where the queue lives, as reducers already were.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

selfhost/backend/emit_call.ludic

@@ -1060,7 +1060,7 @@ function emit_expr(e: Node) -> Val {
   if e.kind == E_STR  { return val(emit_str_const(e.s), "string") }
   if e.kind == E_NEW  {
     if is_slice_ty(e.s) { return emit_new_slice(e.s) }
-    return emit_new_struct(e.s, e.a)
+    return emit_new_struct(e.s, e.a, e.b)
   }
   if e.kind == E_LIST { return emit_list(e) }        # [a, b, c] -> a fresh slice
   # fn name -> the function's address, for a worker entry point. The OS-thread runtime calls it