Export-Metadaten: Umlaut-Fix, xmpMM:VersionID + History

- dc:rights und xmpRights:UsageTerms: Empfaenger -> Empfänger (echte Umlaute)
- Scope-Labels: Vollstaendiger Bericht -> Vollständiger Bericht (zwei Stellen)
- DOCX-Fallback-Text: verfuegbar -> verfügbar
- xmpMM:VersionID: Snapshot-Count der Lage (Proxy fuer Berichts-Revision).
  Router laedt COUNT(*) FROM incident_snapshots und reicht es durch.
- xmpMM:History: Audit-Event pro Export als rdf:Seq-Eintrag mit Timestamp,
  softwareAgent, InstanceID, Scope und Version. Single-Event-Format aus
  pragmatischem Grund (pikepdf-API unterstuetzt keine nativen stEvt-
  Strukturen; Raw-XML-Injection waere dafuer noetig).

src/routers/incidents.py

@@ -1009,6 +1009,13 @@ async def export_incident(
     )
     top_locations = [r["location_name"] for r in await cursor.fetchall() if r["location_name"]]
 
+    # Snapshot-Count (als xmpMM:VersionID im PDF)
+    cursor = await db.execute(
+        "SELECT COUNT(*) AS cnt FROM incident_snapshots WHERE incident_id = ?",
+        (incident_id,),
+    )
+    snapshot_count = (await cursor.fetchone())["cnt"] or 0
+
     # Artikel
     cursor = await db.execute(
         "SELECT * FROM articles WHERE incident_id = ? ORDER BY collected_at DESC",
@@ -1063,6 +1070,7 @@ async def export_incident(
             sections=sections_set,
             organization_name=organization_name,
             top_locations=top_locations,
+            snapshot_count=snapshot_count,
         )
         filename = f"{slug}_{scope_labels_key}_{date_str}.pdf"
         return StreamingResponse(
@@ -1076,6 +1084,7 @@ async def export_incident(
             sections=sections_set,
             organization_name=organization_name,
             top_locations=top_locations,
+            snapshot_count=snapshot_count,
         )
         filename = f"{slug}_{scope_labels_key}_{date_str}.docx"
         return StreamingResponse(