v0.1.0 — Phase 1: Go Backend + SQLite + Seed Data

- Wails project setup (Go + React-TS)
- SQLite schema (allergens, additives, products, week_plans, plan_entries, special_days)
- 14 EU allergens (LMIV 1169/2011)
- 24 German food additives
- 99 products imported from Excel with allergen/additive mappings
- Full Wails bindings (CRUD for products, week plans, entries, special days)
- OTA updater stub (version check against HTTPS endpoint)
- Pure Go SQLite (no CGO) for easy Windows cross-compilation

frontend/src/components/AdditivePicker.tsx

@@ -0,0 +1,129 @@
+import { Additive } from '../types';
+
+interface AdditivePickerProps {
+  additives: Additive[];
+  selectedIds: string[];
+  onChange: (selectedIds: string[]) => void;
+  className?: string;
+}
+
+// Deutsche Namen für häufige Zusatzstoffe (E-Nummern)
+const ADDITIVE_NAMES: Record<string, string> = {
+  '1': 'Farbstoff',
+  '2': 'Konservierungsstoff', 
+  '3': 'Antioxidationsmittel',
+  '4': 'Geschmacksverstärker',
+  '5': 'Geschwefelt',
+  '6': 'Geschwärzt',
+  '7': 'Gewachst',
+  '8': 'Phosphat',
+  '9': 'Süßungsmittel',
+  '10': 'Phenylalaninquelle',
+  '11': 'Koffeinhaltig',
+  '12': 'Chininhaltig',
+  '13': 'Alkoholhaltig',
+  '14': 'Nitritpökelsalz',
+  '15': 'Milchsäure',
+  '16': 'Citronensäure',
+  '17': 'Ascorbinsäure',
+  '18': 'Tocopherol',
+  '19': 'Lecithin',
+  '20': 'Johannisbrotkernmehl',
+  '21': 'Guarkernmehl',
+  '22': 'Xanthan',
+  '23': 'Carrageen',
+  '24': 'Agar'
+};
+
+export function AdditivePicker({ additives, selectedIds, onChange, className = '' }: AdditivePickerProps) {
+  const handleToggle = (additiveId: string) => {
+    if (selectedIds.includes(additiveId)) {
+      onChange(selectedIds.filter(id => id !== additiveId));
+    } else {
+      onChange([...selectedIds, additiveId]);
+    }
+  };
+
+  // Sortierte Zusatzstoffe
+  const sortedAdditives = [...additives].sort((a, b) => {
+    // Numerisch sortieren falls möglich, sonst alphabetisch
+    const aNum = parseInt(a.id);
+    const bNum = parseInt(b.id);
+    if (!isNaN(aNum) && !isNaN(bNum)) {
+      return aNum - bNum;
+    }
+    return a.id.localeCompare(b.id);
+  });
+
+  return (
+    <fieldset className={`border border-gray-300 rounded-md p-4 ${className}`}>
+      <legend className="text-sm font-medium text-gray-900 px-2">
+        Zusatzstoffe auswählen
+      </legend>
+      
+      <div 
+        className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-2 mt-3 max-h-60 overflow-y-auto"
+        role="group"
+        aria-labelledby="additive-picker-legend"
+      >
+        {sortedAdditives.map(additive => {
+          const isSelected = selectedIds.includes(additive.id);
+          const displayName = ADDITIVE_NAMES[additive.id] || additive.name;
+          
+          return (
+            <label
+              key={additive.id}
+              className={`flex items-center space-x-2 p-2 rounded-md border cursor-pointer transition-colors min-h-[44px] ${
+                isSelected 
+                  ? 'bg-orange-100 text-orange-900 border-orange-300' 
+                  : 'bg-white hover:bg-gray-50 border-gray-200'
+              }`}
+            >
+              <input
+                type="checkbox"
+                checked={isSelected}
+                onChange={() => handleToggle(additive.id)}
+                className="w-4 h-4 text-orange-600 bg-gray-100 border-gray-300 rounded focus:ring-orange-500 focus:ring-2"
+                aria-describedby={`additive-${additive.id}-description`}
+              />
+              
+              <span className="flex-1 text-sm">
+                <span className="font-medium">{additive.id}</span>
+                {displayName && (
+                  <span className="text-gray-600 ml-1">
+                    - {displayName}
+                  </span>
+                )}
+              </span>
+              
+              <span 
+                id={`additive-${additive.id}-description`}
+                className="sr-only"
+              >
+                Zusatzstoff {additive.id}: {displayName}
+              </span>
+            </label>
+          );
+        })}
+      </div>
+      
+      {selectedIds.length > 0 && (
+        <div className="mt-4 p-3 bg-orange-50 rounded-md border border-orange-200">
+          <p className="text-sm text-orange-800">
+            <strong>Ausgewählte Zusatzstoffe:</strong>{' '}
+            <span className="font-mono">
+              {selectedIds.sort((a, b) => {
+                const aNum = parseInt(a);
+                const bNum = parseInt(b);
+                if (!isNaN(aNum) && !isNaN(bNum)) {
+                  return aNum - bNum;
+                }
+                return a.localeCompare(b);
+              }).join(', ')}
+            </span>
+          </p>
+        </div>
+      )}
+    </fieldset>
+  );
+}