feat: Sprint 4 complete — frontend MVP (admin dashboard + member portal)

Shadboard starter-kit (Next.js 15 + React 19 + shadcn/ui + Tailwind 4)

Sprint 4.a — Admin Dashboard:
- Auth: NextAuth.js v5, login page, middleware, token rotation
- Dashboard: KPI cards, Recharts stock chart, quick actions
- Members: TanStack Table (search/sort/paginate), add/edit forms
- Distributions: multi-step form, real-time quota check, history
- Stock: batch management, recall dialog, bar chart
- Reports: monthly/member-list/recall, PDF/CSV download, preview

Sprint 4.b — Member Portal:
- Separate route group with top-nav layout (mobile-first)
- Quota dashboard with radial SVG progress indicators
- Distribution history with month filter
- Profile/settings with password change

Cross-cutting:
- i18n: German (default) + English via next-intl
- Dark + light mode (next-themes, user-togglable)
- Playwright E2E tests (6/6 green)
- Docker multi-stage build (node:22-alpine)
- API proxy via Next.js rewrites

Tech: Next.js 15.2.8, React 19, Tailwind 4, NextAuth v5,
TanStack Table, Recharts, Zod, React Hook Form, Playwright

cannamanage-frontend/src/components/pages/not-found-404.tsx

@@ -0,0 +1,31 @@
+import Image from "next/image"
+import Link from "next/link"
+
+import { Button } from "@/components/ui/button"
+
+export function NotFound404() {
+  return (
+    <div className="min-h-screen w-full flex flex-col items-center justify-center gap-y-6 text-center text-foreground bg-background p-4">
+      <div className="flex flex-col-reverse justify-center items-center gap-y-6 md:flex-row md:text-start">
+        <Image
+          src="/images/illustrations/characters/character-02.svg"
+          alt=""
+          height={232}
+          width={249}
+          priority
+        />
+
+        <h1 className="inline-grid text-6xl font-black">
+          404 <span className="text-3xl font-semibold">Page Not Found</span>
+        </h1>
+      </div>
+      <p className="max-w-prose text-xl text-muted-foreground">
+        We couldn&apos;t find the page you&apos;re looking for. It might have
+        been moved or doesn&apos;t exist.
+      </p>
+      <Button size="lg" asChild>
+        <Link href="/">Home Page</Link>
+      </Button>
+    </div>
+  )
+}