feat(api): Ofsted report-card labels and provider-page URL

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB

backend/tests/test_ofsted_codes.py

@@ -0,0 +1,45 @@
+"""Report-card code translation uses the live-sampled Ofsted vocabulary
+(pipeline/scripts/diagnose_compare_gaps.py, TASK 7 VALUE SAMPLE):
+Exceptional / Strong standard / Expected standard / Needs attention /
+Urgent improvement — never the consultation draft's 'Attention needed'."""
+
+from backend.ofsted_codes import (
+    REPORT_CARD_GRADE_NAMES,
+    ofsted_page_url,
+    report_card_labels,
+)
+
+
+def test_scale_is_sampled_vocabulary():
+    assert REPORT_CARD_GRADE_NAMES == {
+        1: "Exceptional",
+        2: "Strong standard",
+        3: "Expected standard",
+        4: "Needs attention",
+        5: "Urgent improvement",
+    }
+
+
+def test_labels_only_for_populated_areas_and_never_safeguarding():
+    ofsted = {
+        "rc_achievement": 2,
+        "rc_inclusion": 3,
+        "rc_attendance_behaviour": 4,
+        "rc_early_years": None,
+        "rc_safeguarding_met": True,
+        "overall_effectiveness": None,
+    }
+    labels = report_card_labels(ofsted)
+    assert labels == {
+        "rc_achievement": {"code": 2, "label": "Strong standard"},
+        "rc_inclusion": {"code": 3, "label": "Expected standard"},
+        "rc_attendance_behaviour": {"code": 4, "label": "Needs attention"},
+    }
+
+
+def test_unknown_code_is_skipped_not_crashed():
+    assert report_card_labels({"rc_achievement": 9}) == {}
+
+
+def test_provider_url():
+    assert ofsted_page_url(138690) == "https://reports.ofsted.gov.uk/provider/21/138690"