Add build automation via Makefile with targets for docker compose
management, DDL application, and data ingestion. Implement a robust bash
script for loading JSONL demo data into Kafka topics with configurable
options for limits, full dataset loading, and topic reset behavior.
Update Kafka broker address to use internal Docker network port (29092)
instead of external port (9092). Add kafka_ingest_plan.md with detailed
implementation strategy and runbook.md with user instructions.
ddadmin