fix(obico): POST image bytes directly to ML API instead of callback URL (#1003)

The ML API previously called back into Bambuddy to fetch snapshots,
  which failed behind reverse proxies with external auth (Authelia, etc.).
  Now the detection loop captures the JPEG locally and POSTs it directly
  as multipart form data — no callback URL, no nonce cache, no
  external_url dependency.

frontend/src/components/FailureDetectionSettings.tsx

@@ -1,7 +1,7 @@
 import { useState, useEffect } from 'react';
 import { useTranslation } from 'react-i18next';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
-import { Loader2, ScanEye, Check, X, AlertTriangle, Info } from 'lucide-react';
+import { Loader2, ScanEye, Check, X, Info } from 'lucide-react';
 import { api } from '../api/client';
 import { Card, CardContent, CardHeader } from './Card';
 import { Button } from './Button';
@@ -221,15 +221,6 @@ export function FailureDetectionSettings() {
               <p className="text-xs text-bambu-gray mt-1">{t('failureDetection.pollIntervalHint')}</p>
             </div>
 
-            {status && !status.external_url_configured && enabled && (
-              <div className="flex items-start gap-2 p-3 bg-amber-900/30 border border-amber-700 rounded text-sm text-amber-200">
-                <AlertTriangle className="w-4 h-4 mt-0.5 flex-shrink-0" />
-                <div>
-                  <div className="font-medium">{t('failureDetection.externalUrlMissing')}</div>
-                  <div className="text-xs mt-1">{t('failureDetection.externalUrlHint')}</div>
-                </div>
-              </div>
-            )}
           </CardContent>
         </Card>