feat(lang): 0.R1 - actions and reducers

action Name { fields } is a typed record; reducer State on Action(s: mut State, a: Action) { ... }
in the module that owns the state takes exactly that state and the action (a second state is
refused); dispatch Action { fields } queues one from anywhere, the queue supplied by the runtime.
The queue is drained at the end of every phase of the frame loop, after every phase of ludic.base's
core_tick_all, and by drain_actions(): in dispatch order, each action's reducers in the order of
their states' names, an action a reducer dispatches queued behind, a queue still growing after 64
rounds stopped with the action named. Examples actions/pack, phases, runaway; rejects for a second
state, a reducer on a non-action and an unknown dispatch; ludic.base's actions_test; LANGUAGE.md.

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

selfhost/backend/emit_vis.ludic

@@ -38,6 +38,8 @@ function vis_check(d: Node, what0: pointer) -> void {
   # 0.S: a state's instance, supplied by the runtime (a component's or a view's glue, an entry's
   # parameters): the code that names it only passes it on
   if d.kind == N_VAR and d.uns == 1 and is_state_ty(d.ty) and len(d.s) > 6 and (d.s[0 .. 6] == "state$") { return }
+  # 0.R: the action queue and the reducers are the runtime's to call, from any module
+  if d.kind == N_FN and (is_action_builtin(d.s) or (len(d.s) > 14 and (d.s[0 .. 14] == "ludic_reduce__"))) { return }
   let what = vis_plain(what0)
   var here = g_err_file
   if here == null { return }