fix: Bugfixes, toten Code entfernt, Cache-Normalisierung & Session

Echte Bugs:
- extractor: JSON-LD-Crash bei Nicht-Dict-Items (isinstance-Guard)
- baseline/__main__: Crawl-Fehler ins Snapshot-Manifest -> erscheinen im Report
- __main__: Whitelist-/Header-/Webshell-Checks nur noch auf status==200
- crawler: Noise-Param-Regex auf Voll-Key (view=/value= nicht mehr verworfen)
- differ/__main__: unerwartetes JSON-LD via eigenem Kanal, auch auf
  unveraenderten Seiten erkannt, kein Re-Alert auf bereits genehmigte Typen

Aufgeraeumt:
- checker: check_internal_paths, find_broken_pages, canonical_is_hijacked,
  check_jsonld_types entfernt (nicht verdrahtet)
- allowed_paths.yaml-Logik und tote Scoring-Keys entfernt
- tote Imports entfernt

Neuer aktiver Schutz:
- Webshell-/Backdoor-Dateinamen-Check verdrahtet (suspicious_filename: 60).
  Regex wortgrenzen-verankert gegen Fehlalarm auf PSEMailerAntispam.js

Effizienz/Struktur:
- crawler nutzt requests.Session (keep-alive)
- Cache-Buster-Normalisierung an einer Stelle (Extraktion) -> stabile
  Snapshots, differ wieder reiner Set-Diff

Tests: 111 gruen (neu: test_checker.py + Regressionstests)
CLAUDE.md aktualisiert

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scanner/baseline.py

@@ -31,9 +31,11 @@ class BaselineManager:
     # Snapshot operations
     # ------------------------------------------------------------------
 
-    def save_snapshot(self, pages: list[dict]) -> Path:
+    def save_snapshot(self, pages: list[dict], errors: list[dict] | None = None) -> Path:
         """
         Persist a crawl+extraction result as a timestamped snapshot.
+        Crawl errors (network failures) are recorded in the manifest so they
+        survive into the comparison/report stage.
         Returns the snapshot directory path.
         """
         ts = _utc_stamp()
@@ -45,6 +47,7 @@ class BaselineManager:
             "timestamp": ts,
             "page_count": len(pages),
             "urls": [p["url"] for p in pages],
+            "errors": errors or [],
         }
         (snap_dir / "manifest.json").write_text(
             json.dumps(manifest, indent=2, ensure_ascii=False), encoding="utf-8"
@@ -71,7 +74,7 @@ class BaselineManager:
     def load_snapshot(self, snap_dir: Optional[Path] = None) -> dict:
         """
         Load a snapshot (default: latest).
-        Returns {manifest, pages: {url: page_dict}, dir: Path}.
+        Returns {manifest, pages: {url: page_dict}, errors: list, dir: Path}.
         """
         if snap_dir is None:
             snap_dir = self.latest_snapshot_dir()
@@ -85,7 +88,12 @@ class BaselineManager:
             page = json.loads(f.read_text(encoding="utf-8"))
             pages[page["url"]] = page
 
-        return {"manifest": manifest, "pages": pages, "dir": snap_dir}
+        return {
+            "manifest": manifest,
+            "pages": pages,
+            "errors": manifest.get("errors", []),
+            "dir": snap_dir,
+        }
 
     # ------------------------------------------------------------------
     # Baseline operations