fix(list): read ofsted grade from fact_ofsted_inspection directly, fix dim_school schema lookup

dim_school.sql was checking for int_ofsted_latest in target.schema (wrong schema)
due to the custom generate_schema_name macro using literal schema names. The
model lives in 'intermediate', so ofsted_grade/date/framework were always NULL
in dim_school, causing all list cards to show 'Not yet inspected'.

Fix 1: data_loader.py joins marts.fact_ofsted_inspection with DISTINCT ON to
get latest inspection per school — no pipeline re-run needed.

Fix 2: dim_school.sql uses schema='intermediate' so future dbt runs correctly
denormalise the Ofsted summary into dim_school.

pipeline/transform/models/marts/dim_school.sql

@@ -6,7 +6,7 @@ with schools as (
 
 {% set ofsted_relation = adapter.get_relation(
     database=target.database,
-    schema=target.schema,
+    schema='intermediate',
     identifier='int_ofsted_latest'
 ) %}