v0.3.0

• Raised the core compatibility floor to agora-etl>=0.2.1
• Updated plugin docs to highlight DeliveryConfig(batch_size=100) for Redis, Kafka, and PostgreSQL source pipelines on the linear lane
• Documented that BatchMiddleware now works correctly with plugin sources that emit one record at a time, matching the agora-etl 0.2.1 runtime fix
• Added regression coverage for running a plugin source through BatchMapMiddleware on the linear lane