feat: add barcode scanner with OpenFoodFacts integration

- Camera-based barcode scanning in FoodSearch using barcode-detector (ZXing WASM)
- Import script to load OFF MongoDB dump into lean openfoodfacts collection
  with kJ→kcal fallback and dedup handling
- Barcode lookup API with live OFF API fallback that caches results locally,
  progressively enhancing the local database
- Add 'off' source to food log, custom meal, and favorite ingredient models
- OpenFoodFact mongoose model for the openfoodfacts collection

src/models/CustomMeal.ts

@@ -2,7 +2,7 @@ import mongoose from 'mongoose';
 
 interface ICustomMealIngredient {
   name: string;
-  source: 'bls' | 'usda' | 'custom';
+  source: 'bls' | 'usda' | 'custom' | 'off';
   sourceId?: string;
   amountGrams: number;
   portions?: { description: string; grams: number }[];
@@ -54,7 +54,7 @@ const PortionSchema = new mongoose.Schema({
 
 const IngredientSchema = new mongoose.Schema({
   name: { type: String, required: true, trim: true },
-  source: { type: String, enum: ['bls', 'usda', 'custom'], required: true },
+  source: { type: String, enum: ['bls', 'usda', 'custom', 'off'], required: true },
   sourceId: { type: String },
   amountGrams: { type: Number, required: true, min: 0 },
   portions: { type: [PortionSchema], default: undefined },

src/models/FavoriteIngredient.ts

@@ -2,7 +2,7 @@ import mongoose from 'mongoose';
 
 const FavoriteIngredientSchema = new mongoose.Schema(
   {
-    source: { type: String, enum: ['bls', 'usda'], required: true },
+    source: { type: String, enum: ['bls', 'usda', 'off'], required: true },
     sourceId: { type: String, required: true },
     name: { type: String, required: true },
     createdBy: { type: String, required: true },
@@ -13,7 +13,7 @@ const FavoriteIngredientSchema = new mongoose.Schema(
 FavoriteIngredientSchema.index({ createdBy: 1, source: 1, sourceId: 1 }, { unique: true });
 
 interface IFavoriteIngredient {
-  source: 'bls' | 'usda';
+  source: 'bls' | 'usda' | 'off';
   sourceId: string;
   name: string;
   createdBy: string;

src/models/FoodLogEntry.ts

@@ -5,7 +5,7 @@ interface IFoodLogEntry {
   date: Date;
   mealType: 'breakfast' | 'lunch' | 'dinner' | 'snack';
   name: string;
-  source: 'bls' | 'usda' | 'recipe' | 'custom';
+  source: 'bls' | 'usda' | 'recipe' | 'custom' | 'off';
   sourceId?: string;
   amountGrams: number;
   per100g: {
@@ -47,7 +47,7 @@ const FoodLogEntrySchema = new mongoose.Schema(
     date: { type: Date, required: true },
     mealType: { type: String, enum: ['breakfast', 'lunch', 'dinner', 'snack'], required: true },
     name: { type: String, required: true, trim: true },
-    source: { type: String, enum: ['bls', 'usda', 'recipe', 'custom'], required: true },
+    source: { type: String, enum: ['bls', 'usda', 'recipe', 'custom', 'off'], required: true },
     sourceId: { type: String },
     amountGrams: { type: Number, required: true, min: 0 },
     per100g: { type: NutritionSnapshotSchema, required: true },

src/models/OpenFoodFact.ts

@@ -0,0 +1,53 @@
+import mongoose from 'mongoose';
+
+interface IOpenFoodFact {
+  barcode: string;
+  name: string;
+  nameDe?: string;
+  brands?: string;
+  category?: string;
+  nutriscore?: string;
+  productQuantityG?: number;
+  serving?: { description: string; grams: number };
+  per100g: {
+    calories: number; protein: number; fat: number; saturatedFat?: number;
+    carbs: number; fiber?: number; sugars?: number;
+    calcium?: number; iron?: number; magnesium?: number; phosphorus?: number;
+    potassium?: number; sodium?: number; zinc?: number;
+    vitaminA?: number; vitaminC?: number; vitaminD?: number; vitaminE?: number;
+    vitaminK?: number; thiamin?: number; riboflavin?: number; niacin?: number;
+    vitaminB6?: number; vitaminB12?: number; folate?: number; cholesterol?: number;
+  };
+}
+
+const ServingSchema = new mongoose.Schema({
+  description: String,
+  grams: Number,
+}, { _id: false });
+
+const Per100gSchema = new mongoose.Schema({
+  calories: Number, protein: Number, fat: Number, saturatedFat: Number,
+  carbs: Number, fiber: Number, sugars: Number,
+  calcium: Number, iron: Number, magnesium: Number, phosphorus: Number,
+  potassium: Number, sodium: Number, zinc: Number,
+  vitaminA: Number, vitaminC: Number, vitaminD: Number, vitaminE: Number,
+  vitaminK: Number, thiamin: Number, riboflavin: Number, niacin: Number,
+  vitaminB6: Number, vitaminB12: Number, folate: Number, cholesterol: Number,
+}, { _id: false });
+
+const OpenFoodFactSchema = new mongoose.Schema({
+  barcode: { type: String, required: true, unique: true, index: true },
+  name: { type: String, required: true },
+  nameDe: String,
+  brands: String,
+  category: String,
+  nutriscore: String,
+  productQuantityG: Number,
+  serving: ServingSchema,
+  per100g: { type: Per100gSchema, required: true },
+}, { collection: 'openfoodfacts' });
+
+let _model: mongoose.Model<IOpenFoodFact>;
+try { _model = mongoose.model<IOpenFoodFact>('OpenFoodFact'); } catch { _model = mongoose.model<IOpenFoodFact>('OpenFoodFact', OpenFoodFactSchema); }
+export const OpenFoodFact = _model;
+export type { IOpenFoodFact };