maven: calendar event querying (task 3)

Store: CalendarEvents(ctx, from, to) — filters caldav facts by key date prefix.
IPC: full wiring through interface, server dispatch, and client.
Router: ParseCalendarDate (сегодня/завтра), CalendarEventFormatter (RU reply).
Voice: calendar detection before notes RAG in IntentQuery handler.
Tests: store integration test, date parser tests, formatter tests.

Co-Authored-By: opencode <opencode@anthropic.com>

internal/router/calendar_test.go

@@ -0,0 +1,26 @@
+package router
+
+import (
+	"testing"
+	"time"
+)
+
+func TestCalendarEventFormatter(t *testing.T) {
+	f := CalendarEventFormatter{}
+	date := time.Date(2026, 7, 6, 0, 0, 0, 0, time.UTC)
+
+	// Empty
+	if got := f.Format(nil, date); got != "на 06.07.2026 ничего нет." {
+		t.Errorf("empty: got %q", got)
+	}
+
+	// One event
+	if got := f.Format([]string{"Standup @ 10:00-10:30"}, date); got != "на 06.07.2026: Standup @ 10:00-10:30" {
+		t.Errorf("one: got %q", got)
+	}
+
+	// Multiple events
+	if got := f.Format([]string{"Standup @ 10:00-10:30", "Lunch @ 12:00-13:00"}, date); got != "на 06.07.2026: Standup @ 10:00-10:30; Lunch @ 12:00-13:00" {
+		t.Errorf("multiple: got %q", got)
+	}
+}