feat(b16): Footer-Label-vs-URL-Slug-Drift-Check (GT URL-STRUCTURE-001)

Erkennt: gängige Footer-Labels / Bookmark- + SEO-Erwartungs-Slugs
(z.B. "Cookie-Richtlinie", "AGB", "Datenschutzerklärung") liefern
404, während das Doc tatsächlich unter einem abweichenden Slug
ausgeliefert wird.

GT-Anker (Elli URL-STRUCTURE-001):
  Footer-Label "Cookie-Richtlinie" → /cookie-richtlinie 404
  Real: /de/cookies
  → externe Bookmarks und Google-Treffer brechen.

Heuristik:
  - Aus auto-discovered URLs Origin + Sprach-Prefix extrahieren
    (z.B. /de, /de-de)
  - Pro doc_type 2-4 kanonische Standard-Slugs probieren (parallel
    via ThreadPoolExecutor, 2s Timeout, HEAD → GET fallback bei 405)
  - Wenn alternative Slug 404/410 → LOW Finding pro doc_type
  - Probe-Cap auf 18 Requests gesamt (Network-Noise-Schutz)
  - Abschaltbar via URL_SLUG_PROBE_DISABLED=1

Severity: LOW (Best-Practice, kein juristisches Hardfail).

Tests: 13/13 grün (Strip-Helper 4 + Origin-Helper 3 + Check-Pfade 6
inkl. mocked _head_status).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend-compliance/compliance/api/agent_check/_b16_wiring.py

@@ -0,0 +1,66 @@
+"""B16 wiring — Footer-Label-vs-URL-Slug-Drift-Detector.
+
+Hängt sich an `state["extra_findings"]` an und rendert einen V2-Block
+(`url_slug_drift_html`).
+"""
+
+from __future__ import annotations
+
+import html
+import logging
+
+from compliance.services.url_slug_drift_check import check_url_slug_drift
+
+logger = logging.getLogger(__name__)
+
+
+def run_b16(state: dict) -> None:
+    new = check_url_slug_drift(state)
+    if not new:
+        return
+    extras = state.get("extra_findings") or []
+    extras.extend(new)
+    state["extra_findings"] = extras
+    state["url_slug_drift_html"] = _render(new)
+    logger.info("B16 url-slug-drift: %d finding(s)", len(new))
+
+
+def _render(findings: list[dict]) -> str:
+    cards = []
+    for f in findings:
+        sev = (f.get("severity") or "").upper()
+        color = "#64748b" if sev == "LOW" else "#f59e0b"
+        alts = f.get("alt_slugs_404") or []
+        alts_html = ""
+        if alts:
+            alts_html = (
+                "<div style='font-size:12px;color:#475569;margin-top:6px;'>"
+                f"<em>404-Slugs: {html.escape(', '.join(alts))}</em></div>"
+            )
+        cards.append(
+            f"<div style='margin:12px 0;padding:14px;background:#fff;"
+            f"border-left:3px solid {color};border-radius:4px;'>"
+            f"<div style='font-weight:600;color:{color};font-size:14px;'>"
+            f"{sev} · {html.escape(f.get('check_id') or '')}</div>"
+            f"<div style='font-size:14px;margin-top:4px;'>"
+            f"<strong>{html.escape(f.get('title') or '')}</strong></div>"
+            f"<div style='font-size:12px;color:#64748b;margin-top:2px;'>"
+            f"{html.escape(f.get('norm') or '')}</div>"
+            f"{alts_html}"
+            f"<div style='font-size:12px;color:#475569;margin-top:6px;'>"
+            f"<em>{html.escape(f.get('evidence') or '')}</em></div>"
+            f"<div style='font-size:13px;margin-top:8px;background:#dcfce7;"
+            f"padding:8px 10px;border-radius:4px;'>"
+            f"<strong>→ Empfehlung:</strong> "
+            f"{html.escape(f.get('action') or '')}</div>"
+            "</div>"
+        )
+    return (
+        "<div style='margin:24px 0;padding:16px;border-left:4px solid #64748b;"
+        "background:#f8fafc;border-radius:4px;'>"
+        "<h2 style='margin:0 0 8px;color:#475569;font-size:16px;'>"
+        "🔗 Standard-Slug-Brüche (SEO / Bookmarks)"
+        "</h2>"
+        + "".join(cards) +
+        "</div>"
+    )

backend-compliance/compliance/api/agent_check/_orchestrator.py

@@ -26,6 +26,7 @@ from ._b12_wiring import run_b12
 from ._b13_wiring import run_b13
 from ._b14_wiring import run_b14
 from ._b15_wiring import run_b15
+from ._b16_wiring import run_b16
 from ._constants import _compliance_check_jobs
 from ._phase_a_resolve import run_phase_a
 from ._phase_b_profile_check import run_phase_b
@@ -76,6 +77,7 @@ async def run_compliance_check(check_id: str, req) -> None:
         run_b13(state)  # Widerrufsbelehrung-Reachability (B2C-Pflicht)
         run_b14(state)  # Widersprüchliche Speicherdauer im selben Doc
         run_b15(state)  # AI-Act Rechtsgrundlage (LLM-Vendor auf lit. f)
+        run_b16(state)  # Footer-Label-vs-URL-Slug-Drift
         # Phase D-3 top/mid/bot: Step 5 HTML blocks
         await run_phase_d3_top(state)
         await run_phase_d3_mid(state)