v2.2.1 - Fix MQTT sync regression

This release fixes a regression introduced in v2.2.0 where timers no longer synced across devices when using the legacy MQTT configuration.

🐛 Fixed

• MQTT sync broken when using default_timer_entity: sensor.* without explicit storage: mqtt
  In v2.2.0, users who relied on the previous implicit behavior experienced timers not syncing between devices.
  This has been restored for full backward compatibility. (See: #84)

✅ What’s restored

• If default_timer_entity is set to a sensor.* and no explicit storage or mqtt: block is defined, the card now correctly infers MQTT storage (as in v2.1.x).
• Existing dashboards should work again without configuration changes.

If you already switched to explicit storage: mqtt configuration, everything will continue to work as expected.