maven: fix test mocks for CalendarEvents interface (verification)

- Add CalendarEvents method to recordingAPI in auth_test.go
- Add CalendarEvents method to fakeCore in handlers_test.go

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

cmd/mavend/tick_test.go

@@ -134,7 +134,7 @@ func TestTickCooldownSuppressesSecondSend(t *testing.T) {
 	sink := &fakeSink{}
 	tl := newTestTickLoop(t, st, sink, nil)
 
-	tl.tick(ctx, now)                 // fires
+	tl.tick(ctx, now)                  // fires
 	tl.tick(ctx, now.Add(time.Minute)) // still within 30m cooldown ⇒ suppressed
 
 	if len(sink.sends) != 1 {