fix(frontend): 修复 diet/index.vue 运行时错误

- selectedIngredients 未在 data 中定义导致模板渲染报错
- addIngredient/removeIngredient/addFood 方法缺少 var self = this

cfc-frontend/pages/diet/index.vue

@@ -129,6 +129,7 @@ export default {
       familyId: null,
       familyMemberId: null,
       ingredients: [],
+      selectedIngredients: [],
       ingredientsLoading: false,
       mealSummary: {},
       trendData: {},
@@ -191,12 +192,14 @@ export default {
       })
     },
     addIngredient(index) {
+      var self = this
       var item = this.ingredients[index]
       addDietIngredient({ food_id: item.foodId, name: item.name }).then(function(res) {
         self.loadIngredients()
       })
     },
     removeIngredient(index) {
+      var self = this
       var item = this.ingredients[index]
       removeDietIngredient({ food_id: item.foodId }).then(function(res) {
         self.loadIngredients()
@@ -268,6 +271,7 @@ export default {
       this.searchResults = []
     },
     addFood(food) {
+      var self = this
       addDietIngredient({ food_id: food.id, name: food.name }).then(function(res) {
         self.closePicker()
         self.loadIngredients()