Release v0.2.1

Changes

Changed

• BREAKING: Renamed WebSocket channel HEARTBEAT to HEARTBEATS to match Coinbase API specification
• Improved JSON parsing macros to check for field existence before parsing (TIMESTAMP_FROM_JSON, NANOSECONDS_FROM_JSON, DOUBLE_FROM_JSON, INT_FROM_JSON)
• Enhanced error logging to combine context and error messages for better debugging

Fixed

• Fixed Order JSON parsing to handle optional fields (edit_history, creation_time, current_pending_replace, attached_order_configuration)
• Fixed Order parsing to support both creation_time and created_time field names
• Fixed WebSocket error handling to properly process and dispatch error messages instead of throwing exceptions
• Fixed user event processing to use correct JSON path for order updates (event.at("orders") instead of j.at("orders"))
• Fixed sequence number checks to handle messages without sequence_num field
• Improved null-safety in JSON parsing throughout order and websocket modules