feat(eu-umbau): Umschalter fuer den KI-Weg in der Oberflaeche

Im Anlege- und Bearbeiten-Dialog einer Lage laesst sich jetzt waehlen, ob sie
ueber den heutigen Weg (Anthropic) oder den EU-Weg (Bedrock Frankfurt + staan)
laeuft; Standard bleibt die Vorgabe der Organisation. Dazu ai_backend in den
Schemas und den Lagen-Endpunkten (Create, Update, Ausgabe), Leerstring setzt
bewusst auf Standard zurueck. In der Lagen-Kopfzeile zeigt ein Kennzeichen
'EU' an, dass die Verarbeitung europaeisch laeuft.

UI-Sync: bewusst NUR online. Der Lokal-Fork hat kein Bedrock-Backend, dort
waere das Feld funktionslos (wie X-Zugaenge und Studio-Gating).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/routers/incidents.py

@@ -22,6 +22,7 @@ router = APIRouter(prefix="/api/incidents", tags=["incidents"])
 INCIDENT_UPDATE_COLUMNS = {
     "title", "description", "type", "status", "refresh_mode",
     "refresh_interval", "refresh_start_time", "retention_days", "international_sources", "include_telegram", "include_x", "visibility",
+    "ai_backend",
 }
 
 
@@ -89,7 +90,7 @@ async def list_incidents(
     query = (
         "SELECT id, title, description, type, status, refresh_mode, refresh_interval, "
         "refresh_start_time, retention_days, visibility, "
-        "international_sources, include_telegram, include_x, created_by, created_at, updated_at, "
+        "international_sources, include_telegram, include_x, ai_backend, created_by, created_at, updated_at, "
         "CASE WHEN summary IS NOT NULL AND summary != '' THEN 1 ELSE 0 END AS has_summary "
         "FROM incidents WHERE tenant_id = ? AND (visibility = 'public' OR created_by = ?)"
     )
@@ -121,8 +122,8 @@ async def create_incident(
     cursor = await db.execute(
         """INSERT INTO incidents (title, description, type, refresh_mode, refresh_interval,
            refresh_start_time, retention_days, international_sources, include_telegram, include_x, visibility,
-           tenant_id, created_by, created_at, updated_at)
-           VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
+           ai_backend, tenant_id, created_by, created_at, updated_at)
+           VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
         (
             data.title,
             data.description,
@@ -135,6 +136,7 @@ async def create_incident(
             1 if data.include_telegram else 0,
             1 if data.include_x else 0,
             data.visibility,
+            data.ai_backend or None,
             tenant_id,
             current_user["id"],
             now,
@@ -385,6 +387,9 @@ async def update_incident(
             continue
         if field in ("international_sources", "include_telegram", "include_x"):
             updates[field] = 1 if value else 0
+        elif field == "ai_backend":
+            # Leerstring = "Vorgabe der Organisation", wird als NULL gespeichert.
+            updates[field] = value or None
         else:
             updates[field] = value