feat: implement meal planning feature with CRUD operations and UI integration

backend/prisma/migrations/20260416100000_add_meal_plan/migration.sql

@@ -0,0 +1,15 @@
+-- CreateTable
+CREATE TABLE `MealPlanEntry` (
+    `id` INTEGER NOT NULL AUTO_INCREMENT,
+    `date` DATE NOT NULL,
+    `recipeId` INTEGER NOT NULL,
+    `createdAt` DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    `updatedAt` DATETIME(3) NOT NULL,
+
+    UNIQUE INDEX `MealPlanEntry_date_key`(`date`),
+    INDEX `MealPlanEntry_date_idx`(`date`),
+    PRIMARY KEY (`id`)
+) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+-- AddForeignKey
+ALTER TABLE `MealPlanEntry` ADD CONSTRAINT `MealPlanEntry_recipeId_fkey` FOREIGN KEY (`recipeId`) REFERENCES `Recipe`(`id`) ON DELETE CASCADE ON UPDATE CASCADE;

backend/prisma/schema.prisma

@@ -69,7 +69,8 @@ model Recipe {
   createdAt    DateTime           @default(now())
   updatedAt    DateTime           @updatedAt
 
-  ingredients RecipeIngredient[]
+  ingredients   RecipeIngredient[]
+  mealPlanEntries MealPlanEntry[]
 }
 
 model RecipeIngredient {
@@ -92,4 +93,16 @@ model PantryItem {
   product   Product  @relation(fields: [productId], references: [id], onDelete: Cascade)
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
+}
+
+model MealPlanEntry {
+  id        Int      @id @default(autoincrement())
+  date      DateTime @db.Date
+  recipe    Recipe   @relation(fields: [recipeId], references: [id], onDelete: Cascade)
+  recipeId  Int
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@unique([date])
+  @@index([date])
 }