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/routes/__root.tsx

@@ -0,0 +1,52 @@
+import { HeadContent, Scripts, createRootRoute } from '@tanstack/react-router'
+import { TanStackRouterDevtoolsPanel } from '@tanstack/react-router-devtools'
+import { TanStackDevtools } from '@tanstack/react-devtools'
+
+import appCss from '../styles.css?url'
+
+const RootDocument = ({ children }: { children: React.ReactNode }) => (
+  <html lang="en">
+    <head>
+      <HeadContent />
+    </head>
+    <body>
+      {children}
+      <TanStackDevtools
+        config={{
+          position: 'bottom-right',
+        }}
+        plugins={[
+          {
+            name: 'Tanstack Router',
+            render: <TanStackRouterDevtoolsPanel />,
+          },
+        ]}
+      />
+      <Scripts />
+    </body>
+  </html>
+)
+
+export const Route = createRootRoute({
+  head: () => ({
+    meta: [
+      {
+        charSet: 'utf-8',
+      },
+      {
+        name: 'viewport',
+        content: 'width=device-width, initial-scale=1',
+      },
+      {
+        title: 'TanStack Start Starter',
+      },
+    ],
+    links: [
+      {
+        rel: 'stylesheet',
+        href: appCss,
+      },
+    ],
+  }),
+  shellComponent: RootDocument,
+})