fix(dbt): declare dim_school -> int_ofsted_latest dependency explicitly

int_ofsted_latest is only ref()'d inside a conditional block, so dbt
couldn't infer the edge and failed to compile dim_school. Add the
-- depends_on hint dbt recommends. No runtime behaviour change: the
adapter.get_relation guard still handles the pre-Ofsted-pipeline case.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pipeline/transform/models/marts/dim_school.sql

@@ -1,5 +1,10 @@
 -- Mart: Canonical school dimension — one row per active URN
 
+-- int_ofsted_latest is only ref()'d inside a conditional block below (it may not
+-- exist before the Ofsted pipeline first runs), so declare the dependency
+-- explicitly for dbt's DAG.
+-- depends_on: {{ ref('int_ofsted_latest') }}
+
 with schools as (
     select * from {{ ref('stg_gias_establishments') }}
 )