feat(pipeline): use GIAS easting/northing for all geocoding, drop postcode step

GIAS grid references are the actual school location — far more accurate
than postcode centroids. Remove geocode_postcodes.py from the daily DAG
and the postcode-not-null filter from dim_location.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pipeline/dags/school_data_pipeline.py

@@ -82,17 +82,12 @@ print(f'Validation passed: {{count}} GIAS rows')
         bash_command=f"cd {PIPELINE_DIR}/transform && {DBT_BIN} build --profiles-dir . --target production --select stg_gias_establishments+ stg_gias_links+ --exclude int_ks2_with_lineage+ int_ks4_with_lineage+",
     )
 
-    geocode_new = BashOperator(
-        task_id="geocode_new",
-        bash_command=f"cd {PIPELINE_DIR} && python scripts/geocode_postcodes.py",
-    )
-
     sync_typesense = BashOperator(
         task_id="sync_typesense",
         bash_command=f"cd {PIPELINE_DIR} && python scripts/sync_typesense.py",
     )
 
-    extract_group >> validate_raw >> dbt_build >> geocode_new >> sync_typesense
+    extract_group >> validate_raw >> dbt_build >> sync_typesense
 
 
 # ── Monthly DAG (Ofsted) ───────────────────────────────────────────────

pipeline/transform/models/marts/dim_location.sql

@@ -22,4 +22,3 @@ select
     end as geom
 from {{ ref('stg_gias_establishments') }} s
 where s.status = 'Open'
-  and s.postcode is not null