feat(cli): Stammdaten-TUI mit Master Data API-Anbindung

- Neue Screens: Kategorien, Lieferanten, Artikel, Kunden (jeweils
  Liste, Detail, Anlegen + Detailaktionen wie Bewertung, Zertifikate,
  Verkaufseinheiten, Lieferadressen, Präferenzen)
- API-Client: Resources für alle 4 Stammdaten-Aggregate implementiert
  (categories, suppliers, articles, customers) mit Mapping von
  verschachtelten Domain-VOs auf flache DTOs
- Lieferant, Artikel, Kategorie: echte HTTP-Calls gegen Backend
  (/api/suppliers, /api/articles, /api/categories, /api/customers)
- 204-No-Content-Endpoints (removeSalesUnit, removeSupplier,
  removeCertificate, removeDeliveryAddress, removeFrameContract)
  lösen Re-Fetch des Aggregats aus
- MasterdataMenu, Navigation-Erweiterung, App.tsx-Routing

frontend/apps/cli/src/components/masterdata/customers/SetPreferencesScreen.tsx

@@ -0,0 +1,89 @@
+import React, { useCallback, useEffect, useState } from 'react';
+import { Box, Text, useInput } from 'ink';
+import type { CustomerPreference } from '@effigenix/api-client';
+import { CUSTOMER_PREFERENCE_LABELS } from '@effigenix/api-client';
+import { useNavigation } from '../../../state/navigation-context.js';
+import { useCustomers } from '../../../hooks/useCustomers.js';
+import { LoadingSpinner } from '../../shared/LoadingSpinner.js';
+import { ErrorDisplay } from '../../shared/ErrorDisplay.js';
+import { client } from '../../../utils/api-client.js';
+
+const ALL_PREFERENCES: CustomerPreference[] = [
+  'BIO', 'REGIONAL', 'TIERWOHL', 'HALAL', 'KOSHER', 'GLUTENFREI', 'LAKTOSEFREI',
+];
+
+function errorMessage(err: unknown): string {
+  return err instanceof Error ? err.message : 'Unbekannter Fehler';
+}
+
+export function SetPreferencesScreen() {
+  const { params, navigate, back } = useNavigation();
+  const customerId = params['customerId'] ?? '';
+  const { setPreferences, loading, error, clearError } = useCustomers();
+
+  const [selectedIndex, setSelectedIndex] = useState(0);
+  const [checked, setChecked] = useState<Set<CustomerPreference>>(new Set());
+  const [initLoading, setInitLoading] = useState(true);
+  const [initError, setInitError] = useState<string | null>(null);
+
+  useEffect(() => {
+    client.customers.getById(customerId)
+      .then((c) => { setChecked(new Set(c.preferences)); setInitLoading(false); })
+      .catch((err: unknown) => { setInitError(errorMessage(err)); setInitLoading(false); });
+  }, [customerId]);
+
+  useInput((_input, key) => {
+    if (initLoading || loading) return;
+    if (key.upArrow) setSelectedIndex((i) => Math.max(0, i - 1));
+    if (key.downArrow) setSelectedIndex((i) => Math.min(ALL_PREFERENCES.length - 1, i + 1));
+    if (_input === ' ') {
+      const pref = ALL_PREFERENCES[selectedIndex];
+      if (pref) {
+        setChecked((prev) => {
+          const next = new Set(prev);
+          if (next.has(pref)) next.delete(pref);
+          else next.add(pref);
+          return next;
+        });
+      }
+    }
+    if (key.return) void handleSave();
+    if (key.escape) back();
+  });
+
+  const handleSave = useCallback(async () => {
+    const updated = await setPreferences(customerId, Array.from(checked));
+    if (updated) navigate('customer-detail', { customerId });
+  }, [customerId, checked, setPreferences, navigate]);
+
+  if (initLoading) return <LoadingSpinner label="Lade Präferenzen..." />;
+  if (initError) return <ErrorDisplay message={initError} onDismiss={back} />;
+  if (loading) return <LoadingSpinner label="Speichere Präferenzen..." />;
+
+  return (
+    <Box flexDirection="column" gap={1}>
+      <Text color="cyan" bold>Präferenzen setzen</Text>
+      {error && <ErrorDisplay message={error} onDismiss={clearError} />}
+
+      <Box flexDirection="column" borderStyle="round" borderColor="gray" paddingX={2} paddingY={1} gap={0}>
+        {ALL_PREFERENCES.map((pref, i) => {
+          const isSelected = i === selectedIndex;
+          const isChecked = checked.has(pref);
+          return (
+            <Box key={pref} gap={1}>
+              <Text color={isSelected ? 'cyan' : 'gray'}>{isSelected ? '▶' : ' '}</Text>
+              <Text color={isChecked ? 'green' : 'gray'}>{isChecked ? '[✓]' : '[ ]'}</Text>
+              <Text color={isSelected ? 'cyan' : 'white'}>{CUSTOMER_PREFERENCE_LABELS[pref]}</Text>
+            </Box>
+          );
+        })}
+      </Box>
+
+      <Box marginTop={1}>
+        <Text color="gray" dimColor>
+          ↑↓ navigieren · Leertaste togglen · Enter speichern · Escape Abbrechen
+        </Text>
+      </Box>
+    </Box>
+  );
+}