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

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

backend/ofsted_codes.py

@@ -39,6 +39,9 @@ def report_card_labels(ofsted: dict) -> dict:
 
 
 def ofsted_page_url(urn: int) -> str:
-    """The school's page on ofsted.gov.uk (all its reports live there —
-    we never deep-link an individual report)."""
-    return f"https://reports.ofsted.gov.uk/provider/21/{urn}"
+    """The school's page on ofsted.gov.uk (all its reports live there — we
+    never deep-link an individual report). Ofsted's provider pages sit under a
+    category (21 primary, 23 secondary, 25 special, 40 FE colleges, …); this
+    address redirects to the right one, where provider/21 404s for every
+    non-primary school."""
+    return f"https://reports.ofsted.gov.uk/inspection-reports/find-inspection-report/provider/ELS/{urn}"