feat(db): add database repositories

Upserts keyed on hiboutikId and deletion of the rows that no longer exist in Hiboutik.

src/database/category.database.repository.ts

@@ -0,0 +1,44 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../../prisma/prisma.service';
+import { Category } from '../../prisma/generated/client';
+import { CategoryCreateInput } from '../../prisma/generated/models/Category';
+
+/** Database access to categories. Rows are matched with Hiboutik by `hiboutikId`. */
+@Injectable()
+export class CategoryDatabaseRepository {
+  constructor(private readonly prisma: PrismaService) {}
+
+  async getAll(): Promise<Category[]> {
+    return this.prisma.category.findMany({
+      orderBy: { hiboutikId: 'asc' },
+    });
+  }
+
+  /** Creates or updates the category with the same `hiboutikId`. */
+  async upsert(category: CategoryCreateInput): Promise<Category> {
+    return this.prisma.category.upsert({
+      where: { hiboutikId: category.hiboutikId },
+      create: category,
+      update: category,
+    });
+  }
+
+  /** Links a category to its parent (null for a root category). Both must already exist. */
+  async setParent(hiboutikId: number, parentHiboutikId: number | null): Promise<Category> {
+    return this.prisma.category.update({
+      where: { hiboutikId },
+      data: { parent: parentHiboutikId ? { connect: { hiboutikId: parentHiboutikId } } : { disconnect: true } },
+    });
+  }
+
+  /**
+   * Deletes the categories that no longer exist in Hiboutik.
+   * Their products and sub-categories are kept: the relation is set to null (onDelete: SetNull).
+   */
+  async deleteMissing(keptHiboutikIds: number[]): Promise<number> {
+    const result = await this.prisma.category.deleteMany({
+      where: { hiboutikId: { notIn: keptHiboutikIds } },
+    });
+    return result.count;
+  }
+}