fix(ofsted): badge and compare read the grade still in force

Search badges date a grade by the inspection that awarded or confirmed it (ofsted_grade_date) and say 'Inspected · year' when the latest inspection gave no grade. ofstedDisplay's kinds become graded / confirmed / no_overall_grade, read from current_grade rather than a carried-forward overall_effectiveness. lib/ofstedStatus.ts holds the two sentences the school and compare pages share.

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

nextjs-app/__tests__/lib/compareLogic.test.ts

@@ -114,16 +114,13 @@ describe('ofstedDisplay', () => {
     expect(d.kind).toBe('report_card');
   });
 
-  it('distinguishes graded from carried-forward grades', () => {
-    const graded = ofstedDisplay(
-      ofsted({ overall_effectiveness: 1, grade_source: 'graded' }),
-    );
-    expect(graded).toMatchObject({ kind: 'graded', gradeLabel: 'Outstanding', carriedForward: false });
-
-    const carried = ofstedDisplay(
-      ofsted({ overall_effectiveness: 2, grade_source: 'ungraded_carried_forward' }),
-    );
-    expect(carried).toMatchObject({ kind: 'carried_forward', gradeLabel: 'Good', carriedForward: true });
+  it('distinguishes a graded grade from a confirmed one', () => {
+    expect(ofstedDisplay(ofsted({ current_grade: { grade: 1, date: '2019-10-09', basis: 'graded' },
+      latest_visit: { date: '2025-02-05', kind: 'ungraded', outcome: 'Some aspects not as strong' } })))
+      .toMatchObject({ kind: 'graded', gradeLabel: 'Outstanding', gradeDate: '2019-10-09' });
+    expect(ofstedDisplay(ofsted({ current_grade: { grade: 2, date: '2024-07-18', basis: 'confirmed' },
+      latest_visit: { date: '2024-07-18', kind: 'ungraded', outcome: 'School remains Good' } })))
+      .toMatchObject({ kind: 'confirmed', gradeLabel: 'Good' });
   });
 
   it('handles missing data', () => {
@@ -131,11 +128,11 @@ describe('ofstedDisplay', () => {
     expect(ofstedDisplay(ofsted({})).kind).toBe('none');
   });
 
-  it('identifies transitional inspections without overall grades', () => {
-    const transitional = ofstedDisplay(
-      ofsted({ overall_effectiveness: null, inspection_date: '2024-11-05' }),
-    );
-    expect(transitional.kind).toBe('transitional');
+  it('has no overall grade when the latest inspection gave none', () => {
+    // Rabbsfarm: the graded inspection's own overall is null, so no grade is
+    // in force even though an older ungraded visit said "remains Good".
+    expect(ofstedDisplay(ofsted({ current_grade: null, overall_effectiveness: null,
+      latest_visit: { date: '2025-06-17', kind: 'graded', outcome: null } })).kind).toBe('no_overall_grade');
   });
 
   it('uses the four legacy grade words', () => {