Add clinic_data_static table creation

Implements create_table_clinic_static() replicating R pipeline's
create_table_clinic_static_data(). Reads clinic_data.xlsx, forward-fills
hierarchical columns, writes parquet. Wired into run_pipeline_cmd (step 3b)
and registered in PARQUET_TO_TABLE for BigQuery upload.

Author: Michael Aydinbas

a4d-python/src/a4d/tables/clinic.py

@@ -0,0 +1,67 @@
+"""Create clinic static data table from reference data.
+
+Replicates R pipeline's create_table_clinic_static_data() function:
+reads clinic_data.xlsx, fills down hierarchical columns, exports as parquet.
+"""
+
+from pathlib import Path
+
+import polars as pl
+from loguru import logger
+
+from a4d.reference.loaders import find_reference_data_dir
+
+# Text columns filled downward to handle merged/blank cells in the Excel sheet.
+# R: tidyr::fill(country_code:clinic_id, .direction = "down")
+_FILL_COLUMNS = [
+    "country",
+    "clinic_province",
+    "clinic_name",
+    "clinic_status",
+    "clinic_id",
+    "country_code",
+    "clinic_code",
+    "patient_id_example",
+]
+
+
+def create_table_clinic_static(output_dir: Path) -> Path:
+    """Create clinic static data table from reference data.
+
+    Reads clinic_data.xlsx from reference_data/, fills hierarchical columns
+    downward (matching R's tidyr::fill behaviour), and writes parquet.
+
+    Args:
+        output_dir: Directory to write the parquet file
+
+    Returns:
+        Path to created clinic_data_static.parquet
+    """
+    reference_dir = find_reference_data_dir()
+    clinic_file = reference_dir / "clinic_data.xlsx"
+
+    if not clinic_file.exists():
+        raise FileNotFoundError(f"Clinic data file not found: {clinic_file}")
+
+    logger.info(f"Reading clinic data from: {clinic_file}")
+
+    df = pl.read_excel(clinic_file, sheet_id=1)
+
+    # Drop unnamed index column — R: select(2:11)
+    unnamed_cols = [c for c in df.columns if c.startswith("__UNNAMED")]
+    if unnamed_cols:
+        df = df.drop(unnamed_cols)
+
+    # Fill nulls downward for hierarchical columns — R: tidyr::fill(..., .direction = "down")
+    fill_cols = [c for c in _FILL_COLUMNS if c in df.columns]
+    if fill_cols:
+        df = df.with_columns([pl.col(c).forward_fill() for c in fill_cols])
+
+    logger.info(f"Clinic static data: {df.shape[0]} rows, {df.shape[1]} columns")
+
+    output_dir.mkdir(parents=True, exist_ok=True)
+    output_file = output_dir / "clinic_data_static.parquet"
+    df.write_parquet(output_file)
+
+    logger.info(f"Clinic static table saved: {output_file}")
+    return output_file