feat: add CLI refresh command for pathway data (Task 2.1)

Add cli/refresh_pathways.py with:
- refresh_pathways() main function for full pipeline orchestration
- insert_pathway_records() for SQLite insertion
- log_refresh_start/complete/failed() for refresh tracking
- CLI with --minimum-patients, --provider-codes, --dry-run, --verbose

Uses existing pipeline functions:
- fetch_and_transform_data() from pathway_pipeline.py
- process_all_date_filters() for 6 date filter combinations
- Schema helpers from data_processing/schema.py

cli/__init__.py

@@ -0,0 +1,6 @@
+"""
+CLI commands for NHS High-Cost Drug Patient Pathway Analysis Tool.
+
+Available commands:
+    python -m cli.refresh_pathways  - Refresh pathway data from Snowflake
+"""