MP3 Player Library U2.1 Modular
=======================

Requires:
- ESP32
- ProjectUNION Core 0.3.1 and ProjectUNION MQTT 0.3.1
- PubSubClient
- DFRobotDFPlayerMini

Hardware:
- ESP32 RX2 GPIO16 <- DFPlayer TX
- ESP32 TX2 GPIO17 -> DFPlayer RX
- Common GND
- DFPlayer powered according to the existing project wiring

ProjectUNION owns:
- WiFi, setup hotspot, hostname and mDNS
- language, web layout and common pages
- firmware update
- MQTT broker, TLS, reconnect, test and status

MP3 Player owns:
- DFPlayer Mini
- Play, Stop, Pause, Volume and Track commands
- project-specific MQTT topics
- MP3 test and configuration pages

Legacy migration:
The first start reads the old configuration from namespace:

  mp3player

and migrates:
- WiFi and hostname
- language
- MQTT broker, port, user, password and TLS
- base topic and command topics
- start volume

The old configuration is not deleted.

Recommended test:
1. Upload by USB
2. Verify WiFi and hostname
3. Verify MQTT settings and connection
4. Check migrated MP3 topics
5. Test track and volume from the web page
6. Test all commands through MQTT


Changes in U2.1 Modular
-----------------------
- Updated for the modular ProjectUNION architecture.
- Uses ProjectUNION Core 0.3.1.
- Uses ProjectUNION MQTT 0.3.1.
- Does not include or depend on ProjectUNION DCC or NmraDcc.
- MP3, web configuration and MQTT functionality are unchanged.
