feat: complete Task 2.2 - test refresh pipeline with Snowflake data

Tested full refresh pipeline end-to-end with real Snowflake data:
- Fixed trust filter to read Name column from defaultTrusts.csv
- Fixed Decimal type handling in calculate_cost_per_patient_per_annum
- Fixed array handling in convert_to_records for average_administered
- Added required reference CSV files to data/ directory
- Configured Snowflake connection (account, warehouse, user)

Results:
- Snowflake fetch: 656,695 records in ~7s
- Transformations: 519,848 records after UPID/drug/directory
- Pathway nodes: 293 for all_6mo (8 trusts, 14 directories)
- Total processing time: ~6.2 minutes

data/directory_list.csv

@@ -0,0 +1,58 @@
+directory
+ACCIDENT & EMERGENCY
+ANAESTHETICS
+ANTICOAGULANT SERVICE
+AUDIOLOGY
+BLOOD AND MARROW TRANSPLANTATION
+BREAST SURGERY
+CARDIOLOGY
+CARDIOTHORACIC TRANSPLANTATION
+CHEMICAL PATHOLOGY
+CLINICAL HAEMATOLOGY
+CLINICAL IMMUNOLOGY
+CLINICAL NEUROPHYSIOLOGY
+CLINICAL ONCOLOGY (PREVIOUSLY RADIOTHERAPY)
+COLORECTAL SURGERY
+CRITICAL CARE MEDICINE
+DERMATOLOGY
+DIABETIC MEDICINE
+DIETETICS
+ENDOCRINOLOGY
+ENT
+GASTROENTEROLOGY
+GENERAL MEDICINE
+GENERAL SURGERY
+GERIATRIC MEDICINE
+GYNAECOLOGICAL ONCOLOGY
+GYNAECOLOGY
+INFECTIOUS DISEASES
+MEDICAL ONCOLOGY
+MEDICAL OPHTHALMOLOGY
+MIDWIFE EPISODE
+NEONATOLOGY
+NEPHROLOGY
+NEUROLOGY
+NEUROSURGERY
+OBSTETRICS
+OPHTHALMOLOGY
+ORAL SURGERY
+ORTHOPTICS
+ORTHOTICS
+PAEDIATRIC CARDIOLOGY
+PAEDIATRIC DIABETIC MEDICINE
+PAEDIATRIC GASTROENTEROLOGY
+PAEDIATRIC UROLOGY
+PAEDIATRICS
+PAIN MANAGEMENT
+PLASTIC SURGERY
+REHABILITATION
+RHEUMATOLOGY
+STROKE MEDICINE
+THORACIC MEDICINE
+THORACIC SURGERY
+TRANSIENT ISCHAEMIC ATTACK
+TRANSPLANTATION SURGERY
+TRAUMA & ORTHOPAEDICS
+UPPER GASTROINTESTINAL SURGERY
+UROLOGY
+VASCULAR SURGERY