fix(audit): P90-Diagnose — verbose Exception fuer fetch+auto-discovery

BMW-Lauf 760de886 hat 0 cmp_payloads obwohl consent-tester ePaaS 4x captured.
Backend-Log zeigt 'Consent-tester fetch failed for ...anbieterkennzeichnung.html: '
mit LEEREM Exception-String. Auch 'auto-discovery failed for https://www.bmw.de/: '
ist leer. Quick-Fix: str(e) + type(e).__name__ in beiden Except-Bloecken,
damit naechster BMW-Lauf den echten Fehler sichtbar macht.

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

backend-compliance/compliance/api/agent_compliance_check_routes.py

@@ -1271,7 +1271,9 @@ async def _fetch_text(url: str, doc_type: str = "") -> tuple[str, list[dict]]:
                     fallback_text = merged or cmp_cookie_text or ""
                     return fallback_text, cmp_payloads
     except Exception as e:
-        logger.warning("Consent-tester fetch failed for %s: %s", url, e)
+        # P90: verbose exception fuer Diagnose (war vorher empty)
+        logger.warning("Consent-tester fetch failed for %s: %s (%s)",
+                       url, str(e) or "(empty)", type(e).__name__)
 
     # 2. Fallback: direct HTTP fetch (works for SSR pages like BMW).
     # P7: kenntlicher UA + per-Domain Rate-Limit.
@@ -1416,7 +1418,9 @@ async def _autodiscover_missing(
                             len(body.get("cmp_payloads") or []),
                             len(cmp_text.split()))
         except Exception as e:
-            logger.warning("auto-discovery failed for %s: %s", base, e)
+            # P90: verbose exception fuer Diagnose
+            logger.warning("auto-discovery failed for %s: %s (%s)",
+                           base, str(e) or "(empty)", type(e).__name__)
 
     # Classify each discovered doc into a canonical doc_type
     by_type: dict[str, dict] = {}