Enhance checkout flow with new components and validation

- Added AddressForm and CheckoutForm components for user input during checkout.
- Implemented validation using Zod and VeeValidate for billing address fields.
- Created OrderSummary and MockPayPalButton components for order confirmation and payment simulation.
- Updated CartSheet and CartSidebar to navigate to the new checkout page at '/kasse'.
- Introduced new API endpoints for validating checkout data and creating orders.
- Enhanced user experience with responsive design and error handling.

These changes complete the checkout functionality, allowing users to enter billing information, simulate payment, and confirm orders.

server/api/orders/[id].get.ts

@@ -0,0 +1,89 @@
+/**
+ * GET /api/orders/[id]
+ *
+ * Fetch order details by ID
+ *
+ * Security:
+ * - Requires authentication
+ * - Users can only access their own orders
+ *
+ * Response:
+ * {
+ *   id: string
+ *   orderNumber: string
+ *   totalAmount: string
+ *   status: string
+ *   billingAddress: BillingAddress
+ *   items: OrderItem[]
+ *   createdAt: Date
+ * }
+ */
+
+import { eq, and } from 'drizzle-orm'
+import { orders, orderItems } from '../../database/schema'
+
+export default defineEventHandler(async (event) => {
+  // Require authentication
+  const { user } = await requireUserSession(event)
+
+  // Get order ID from URL parameter
+  const orderId = getRouterParam(event, 'id')
+
+  if (!orderId) {
+    throw createError({
+      statusCode: 400,
+      statusMessage: 'Order ID is required',
+    })
+  }
+
+  const db = useDatabase()
+
+  // Fetch order with items
+  const order = await db.query.orders.findFirst({
+    where: and(eq(orders.id, orderId), eq(orders.userId, user.id)),
+    with: {
+      items: {
+        with: {
+          product: true,
+        },
+      },
+    },
+  })
+
+  if (!order) {
+    throw createError({
+      statusCode: 404,
+      statusMessage: 'Order not found',
+    })
+  }
+
+  // Transform items to include price and product snapshot data
+  const transformedItems = order.items.map((item: any) => ({
+    id: item.id,
+    orderId: item.orderId,
+    productId: item.productId,
+    quantity: item.quantity,
+    priceSnapshot: item.priceSnapshot,
+    productSnapshot: item.productSnapshot,
+    product: {
+      id: item.product.id,
+      name: item.product.name,
+      description: item.product.description,
+      imageUrl: item.product.imageUrl,
+    },
+    subtotal: Number.parseFloat(item.priceSnapshot) * item.quantity,
+  }))
+
+  return {
+    id: order.id,
+    orderNumber: order.orderNumber,
+    totalAmount: order.totalAmount,
+    status: order.status,
+    billingAddress: order.billingAddress,
+    items: transformedItems,
+    paymentId: order.paymentId,
+    paymentCompletedAt: order.paymentCompletedAt,
+    createdAt: order.createdAt,
+    updatedAt: order.updatedAt,
+  }
+})