Add comprehensive DAG implementation for ClickHouse schema initialization
and ETL pipeline orchestration. The ddl_init_dag manages database schema
creation across stg/ods/dds/dm layers with verification capabilities. The
etl_pipeline_dag implements full ODS to DDS to DM transformation flow with
data quality checks, branching logic for full/incremental loads, and
timeout handling for data availability.
Additional changes:
- Upgrade Airflow from 2.9.3 to 2.10.5
- Fix ClickHouse connection to use native protocol port 9000
- Mount SQL directory in docker-compose for DAG execution
- Update project requirements and documentation comments
- Remove unused pandas dependency
