This commit refactors the chat application to transmit MQTT messages using a structured JSON format.
The struct, leveraging , now encapsulates both the username and the message content, allowing them to be sent and received as distinct fields.
Key changes include:
- Added and dependencies to .
- Defined a struct with and fields.
- Modified message publishing to serialize instances to JSON.
- Updated message receiving to deserialize JSON payloads into instances.
- Adjusted internal message storage and display logic to handle the separate username and message components.
- Ensured the connect message also uses the new structured format.
