fix(api): inspectorate and Ofsted listing in payloads; Ofsted links that resolve (H4)

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

backend/tests/test_ofsted_codes.py

@@ -42,4 +42,4 @@ def test_unknown_code_is_skipped_not_crashed():
 
 
 def test_provider_url():
-    assert ofsted_page_url(138690) == "https://reports.ofsted.gov.uk/provider/21/138690"
+    assert ofsted_page_url(138690) == "https://reports.ofsted.gov.uk/inspection-reports/find-inspection-report/provider/ELS/138690"