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>

packages/ludic.base/system.ludic

@@ -63,6 +63,7 @@ export function core_tick_all(base_st: mut BaseState, t: Tick) -> void {
     for i in 0 .. len(all) {
       if all[i].phase == ph and all[i].tick != null { all[i].tick(t) }
     }
+    drain_actions()                              # 0.R: the phase's actions, reduced before the next
   }
 }