fix(pipeline): dim_school's Ofsted grade is the one still in force

dim_school.ofsted_grade (Typesense's rating) coalesced the graded grade with an older ungraded visit's, so Rabbsfarm's 2020 'remains Good' survived its 2025 no-grade inspection. It now reads int_ofsted_latest's current_grade, and ofsted_date is the latest visit. Unit tests pin both (audit C1, M1).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pipeline/transform/models/marts/dim_school.sql

@@ -71,12 +71,12 @@ select
     s.nursery_provision,
     s.admissions_policy_code,
 
-    -- Latest Ofsted (populated after monthly Ofsted pipeline runs)
+    -- Latest Ofsted (populated after monthly Ofsted pipeline runs). The grade
+    -- still in force and the latest visit, from int_ofsted_latest — never a
+    -- grade carried past a newer inspection.
     {% if ofsted_relation is not none %}
-    -- Prefer the graded overall effectiveness; fall back to the grade parsed
-    -- from the latest ungraded (Section 8) outcome when no graded grade exists.
-    coalesce(o.overall_effectiveness, o.ungraded_grade) as ofsted_grade,
-    o.inspection_date as ofsted_date,
+    o.current_grade as ofsted_grade,
+    o.latest_visit_date as ofsted_date,
     o.framework as ofsted_framework
     {% else %}
     null::text as ofsted_grade,