Implement ordering MVP domain layer per spec (issue #1)

Scaffolds the TanStack Start + Drizzle/Postgres + Better Auth app and
implements the core ordering domain: menu browsing, guest/account order
placement with online payment, per-Order-Item independent cooking and
cancellation, dynamic Machine-Tag pool assignment, and multi-step recipes
(see docs/adr/0001-0003). Adds a guest-access-token / session-based
ownership check on every read/mutation so an order can't be viewed,
cancelled, or picked up by anyone but its owner.

Covered by 14 tests running the domain layer directly against a real,
ephemeral Postgres (testcontainers) — createServerFn couldn't be called
outside a real request context, so tests exercise the domain functions the
server functions thinly wrap instead of the server functions themselves.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/db/seed.ts

@@ -0,0 +1,96 @@
+import type { NodePgDatabase } from 'drizzle-orm/node-postgres'
+
+import * as schema from '#/db/schema.ts'
+
+// Sample Brand/menu/hardware data for local dev and as the shared fixture
+// tests seed against. Specific menu items are explicitly out of scope for
+// the ordering spec — Pizza/Burger here are illustrative, not final content.
+export const seedGhostKitchen = async (db: NodePgDatabase<typeof schema>) => {
+  const [brand] = await db
+    .insert(schema.brands)
+    .values({ name: 'Ghost Kitchen' })
+    .returning()
+
+  const [ovenTag] = await db
+    .insert(schema.machineTags)
+    .values({ name: 'oven' })
+    .returning()
+  const [grillTag] = await db
+    .insert(schema.machineTags)
+    .values({ name: 'grill' })
+    .returning()
+  const [assemblyTag] = await db
+    .insert(schema.machineTags)
+    .values({ name: 'assembly' })
+    .returning()
+
+  const [oven1] = await db
+    .insert(schema.machines)
+    .values({ name: 'Oven 1', machineTagId: ovenTag.id })
+    .returning()
+  const [grill1] = await db
+    .insert(schema.machines)
+    .values({ name: 'Grill 1', machineTagId: grillTag.id })
+    .returning()
+  const [assembly1] = await db
+    .insert(schema.machines)
+    .values({ name: 'Assembly Station 1', machineTagId: assemblyTag.id })
+    .returning()
+
+  const [pizza] = await db
+    .insert(schema.menuItems)
+    .values({
+      brandId: brand.id,
+      name: 'Pizza',
+      description: 'Classic oven-baked pizza.',
+      priceCents: 1299,
+    })
+    .returning()
+
+  await db.insert(schema.menuItemSteps).values({
+    menuItemId: pizza.id,
+    sequence: 1,
+    machineTagId: ovenTag.id,
+    estimatedDurationSeconds: 600,
+  })
+
+  const [burger] = await db
+    .insert(schema.menuItems)
+    .values({
+      brandId: brand.id,
+      name: 'Burger',
+      description: 'Grilled burger, assembled to order.',
+      priceCents: 999,
+    })
+    .returning()
+
+  await db.insert(schema.menuItemSteps).values([
+    {
+      menuItemId: burger.id,
+      sequence: 1,
+      machineTagId: grillTag.id,
+      estimatedDurationSeconds: 240,
+    },
+    {
+      menuItemId: burger.id,
+      sequence: 2,
+      machineTagId: assemblyTag.id,
+      estimatedDurationSeconds: 90,
+    },
+  ])
+
+  return {
+    brand,
+    machineTags: { oven: ovenTag, grill: grillTag, assembly: assemblyTag },
+    machines: { oven1, grill1, assembly1 },
+    menuItems: { pizza, burger },
+  }
+}
+
+if (import.meta.url === `file://${process.argv[1]}`) {
+  const { drizzle } = await import('drizzle-orm/node-postgres')
+  const db = drizzle(process.env.DATABASE_URL!, { schema })
+  await seedGhostKitchen(db)
+  console.log('Seeded Ghost Kitchen sample data.')
+  process.exit(0)
+}