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.

scripts/add-to-cart.ts

@@ -0,0 +1,86 @@
+/**
+ * Add product to cart for testing
+ */
+import { drizzle } from 'drizzle-orm/postgres-js'
+import postgres from 'postgres'
+import * as schema from '../server/database/schema'
+import { eq } from 'drizzle-orm'
+
+const { products, carts, cartItems, users } = schema
+
+const connectionString = process.env.DATABASE_URL || 'postgresql://dev:dev_password_change_me@localhost:5432/experimenta_dev'
+const client = postgres(connectionString)
+const db = drizzle(client, { schema })
+
+async function addToCart() {
+  console.log('🛒 Adding products to cart for test user...')
+
+  // Get any user (the first one)
+  const user = await db.query.users.findFirst()
+
+  if (!user) {
+    console.error('❌ No users found. Please login first.')
+    await client.end()
+    process.exit(1)
+  }
+
+  console.log(`  ✓ Found user: ${user.email} (ID: ${user.id})`)
+
+  // Get or create cart
+  let cart = await db.query.carts.findFirst({
+    where: eq(carts.userId, user.id),
+  })
+
+  if (!cart) {
+    const [newCart] = await db.insert(carts).values({ userId: user.id }).returning()
+    cart = newCart
+    console.log(`  ✓ Created cart: ${cart.id}`)
+  } else {
+    console.log(`  ✓ Found cart: ${cart.id}`)
+  }
+
+  // Get first product
+  const product = await db.query.products.findFirst({
+    where: eq(products.active, true),
+  })
+
+  if (!product) {
+    console.error('❌ No active products found.')
+    await client.end()
+    process.exit(1)
+  }
+
+  console.log(`  ✓ Found product: ${product.name} (${product.price}€)`)
+
+  // Check if item already exists
+  const existingItem = await db.query.cartItems.findFirst({
+    where: (item, { and, eq }) => and(eq(item.cartId, cart.id), eq(item.productId, product.id)),
+  })
+
+  if (existingItem) {
+    console.log(`  ℹ Product already in cart, skipping...`)
+    console.log(`✅ Cart ready for checkout!`)
+    await client.end()
+    return
+  }
+
+  // Add to cart
+  const [cartItem] = await db
+    .insert(cartItems)
+    .values({
+      cartId: cart.id,
+      productId: product.id,
+      quantity: 2,
+    })
+    .returning()
+
+  console.log(`  ✓ Added ${cartItem.quantity}x "${product.name}" to cart`)
+  console.log(`✅ Cart ready for checkout!`)
+
+  await client.end()
+}
+
+addToCart().catch((error) => {
+  console.error('❌ Error:', error)
+  process.exit(1)
+})