Split actions.go into per-intent files

Pure move: actionFact, actionReminder, actionAct and actionNote each get
their own actions_<intent>.go. The two small ones (chat, system) and the
actionHandlers table stay in actions.go, which is now just the dispatch
layer and the notes about what does not belong in it. No behaviour
change — only the file a handler is read in.

cmd/mavend/actions_reminder.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"context"
+	"log"
+
+	"github.com/kami/maven/internal/router"
+)
+
+// actionReminder handles router.IntentReminder: parse the time when stage-0
+// skipped the extractor, then create the reminder.
+func (h *reactiveHandler) actionReminder(ctx context.Context, dec router.Decision) string {
+	if !dec.Slots.HasTime {
+		// Stage-0 (reminder-wakeword grammar) skips the extractor, so the
+		// time wasn't parsed. Run the parser as a fallback.
+		if dec.Stage == 0 && h.timeParser != nil {
+			t, ok, err := h.timeParser.Parse(ctx, dec.Utterance, h.now())
+			if err == nil && ok {
+				dec.Slots.Time = t
+				dec.Slots.HasTime = true
+			}
+		}
+		if !dec.Slots.HasTime {
+			return "не получилось разобрать время напоминания."
+		}
+	}
+	payload := `{"text":` + jsonString(dec.Utterance) + `}`
+	if _, err := h.api.CreateReminder(ctx, dec.Slots.Time, payload, ""); err != nil {
+		log.Printf("voice: create reminder: %v", err)
+		return "не получилось поставить напоминание."
+	}
+	return ""
+}