feat(backup): admin and account UI for server backups, import by section

Admin settings: switch, time, retention, list with download and a
"Jetzt sichern" button. Account settings: own server backups with
download and restore (replace or add, for chosen sections, replace needs
a second tap). The MindSift import gets the same section picker.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/settings/ImportCard.tsx

@@ -1,6 +1,7 @@
 import React, { useRef, useState } from 'react';
 import { Upload, Check, AlertCircle, FileArchive } from 'lucide-react';
-import { ImportSummary } from '../../lib/types';
+import { DATA_SECTIONS, DataSection, ImportSummary } from '../../lib/types';
+import { SectionPicker } from './SectionPicker';
 import { api } from '../../lib/api';
 
 interface ImportCardProps {
@@ -18,6 +19,7 @@ const summaryParts = (s: ImportSummary) =>
     s.tasks && `${s.tasks} Aufgabe${s.tasks === 1 ? '' : 'n'}`,
     s.lists && `${s.lists} Liste${s.lists === 1 ? '' : 'n'} mit ${s.listItems} Einträgen`,
     s.inbox && `${s.inbox} Gedanke${s.inbox === 1 ? '' : 'n'} für die Triage`,
+    s.themes && `${s.themes} Theme${s.themes === 1 ? '' : 's'}`,
   ].filter(Boolean) as string[];
 
 // One import path: drop or pick a file, see a preview of what would be created, then import.
@@ -33,6 +35,9 @@ export const ImportCard: React.FC<ImportCardProps> = ({ source, title, descripti
   // MindSift data can replace the current state instead of being added next to it
   const [mode, setMode] = useState<'merge' | 'restore'>('merge');
   const [confirmRestore, setConfirmRestore] = useState(false);
+  // MindSift data: which parts to take from the file
+  const [sections, setSections] = useState<DataSection[]>(DATA_SECTIONS.map((s) => s.id));
+  const sectionParam = source === 'mindsift' ? sections : undefined;
   const restoring = source === 'mindsift' && mode === 'restore';
 
   const reset = () => {
@@ -49,7 +54,7 @@ export const ImportCard: React.FC<ImportCardProps> = ({ source, title, descripti
     setFile(f);
     setBusy(true);
     try {
-      setPreview(await api.importData(source, f, true));
+      setPreview(await api.importData(source, f, true, 'merge', sectionParam));
     } catch (err: any) {
       setError(err.message || 'Datei konnte nicht gelesen werden');
     } finally {
@@ -62,7 +67,7 @@ export const ImportCard: React.FC<ImportCardProps> = ({ source, title, descripti
     setBusy(true);
     setError(null);
     try {
-      setResult(await api.importData(source, file, false, restoring ? 'restore' : 'merge'));
+      setResult(await api.importData(source, file, false, restoring ? 'restore' : 'merge', sectionParam));
       setFile(null);
       setPreview(null);
       setConfirmRestore(false);
@@ -87,7 +92,7 @@ export const ImportCard: React.FC<ImportCardProps> = ({ source, title, descripti
           {(
             [
               ['merge', 'Hinzufügen', 'Bestehende Daten behalten, Backup daneben anlegen.'],
-              ['restore', 'Wiederherstellen', 'Eigene Notizen, Aufgaben und Listen vorher löschen.'],
+              ['restore', 'Wiederherstellen', 'Gewählte Bereiche vorher leeren.'],
             ] as const
           ).map(([value, label, text]) => (
             <button
@@ -114,6 +119,24 @@ export const ImportCard: React.FC<ImportCardProps> = ({ source, title, descripti
         </div>
       )}
 
+      {source === 'mindsift' && (
+        <SectionPicker
+          value={sections}
+          onChange={(next) => {
+            setSections(next);
+            // The preview depends on the sections, so a picked file is read again
+            if (file) {
+              setBusy(true);
+              api
+                .importData(source, file, true, 'merge', next)
+                .then(setPreview)
+                .catch((err) => setError(err.message))
+                .finally(() => setBusy(false));
+            }
+          }}
+        />
+      )}
+
       <div
         onDragOver={(e) => {
           e.preventDefault();
@@ -194,8 +217,9 @@ export const ImportCard: React.FC<ImportCardProps> = ({ source, title, descripti
                 className="mt-0.5 w-4 h-4 shrink-0"
               />
               <span>
-                <strong className="text-status-err">Achtung:</strong> Alle deine bisherigen Notizen, Ordner, Aufgaben, Gedanken und
-                Listen werden vor dem Import unwiderruflich gelöscht und durch das Backup ersetzt. Mit dir geteilte Inhalte anderer
+                <strong className="text-status-err">Achtung:</strong> Deine bisherigen Daten in den gewählten Bereichen
+                ({DATA_SECTIONS.filter((x) => sections.includes(x.id)).map((x) => x.label).join(', ')}) werden vor dem Import
+                unwiderruflich gelöscht und durch das Backup ersetzt. Mit dir geteilte Inhalte anderer
                 bleiben erhalten.
               </span>
             </label>