fix(school): the Ofsted section shows the grade still in force and the latest visit

The section is dated by the latest visit and headlines the grade still in force with the inspection that awarded or confirmed it, or 'No overall grade'. A later visit that isn't the grade's source gets its own line, with an ungraded outcome such as 'Standards maintained'. The primary and secondary no-grade branches merge, so the secondary page no longer drops the sixth-form and early-years judgements (audit M2), and 'Not rated' goes.

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

nextjs-app/__tests__/support/schoolFixtures.ts

@@ -191,7 +191,8 @@ export const primaryFixture = {
     personal_development: 2,
     leadership_management: 2,
     previous_overall: 3,
-    grade_source: 'graded',
+    current_grade: { grade: 2, date: '2023-05-17', basis: 'graded' },
+    latest_visit: { date: '2023-05-17', kind: 'graded', outcome: null },
   }),
   census,
   admissions: makeAdmissions({ year: 2024 }),
@@ -295,7 +296,8 @@ export const allThroughFixture = {
     behaviour_attitudes: 1,
     personal_development: 1,
     leadership_management: 1,
-    grade_source: 'graded',
+    current_grade: { grade: 1, date: '2022-10-04', basis: 'graded' },
+    latest_visit: { date: '2022-10-04', kind: 'graded', outcome: null },
   }),
   census,
   admissions: makeAdmissions({ year: 2024, school_phase: 'Secondary' }),