feat: dashboard UI with product cards + sparklines

src/app/page.tsx

@@ -1,3 +1,63 @@
-export default function Home() {
-  return <main className="p-8"><h1 className="text-2xl">Preis-Tracker</h1></main>
+import Link from 'next/link'
+import { desc, eq, sql } from 'drizzle-orm'
+import { db, products, priceSnapshots } from '@/lib/db'
+import { ProductCard } from '@/components/ProductCard'
+
+export const dynamic = 'force-dynamic'
+
+export default async function Home() {
+  const rows = await db.execute<{
+    id: string; url: string; shop: string; name: string; image_url: string | null;
+    last_price: string | null; min_price: string | null;
+  }>(sql`
+    select p.id, p.url, p.shop, p.name, p.image_url,
+      (select price from price_snapshots s where s.product_id = p.id and s.price is not null order by scraped_at desc limit 1) as last_price,
+      (select min(price) from price_snapshots s where s.product_id = p.id and s.price is not null) as min_price
+    from products p where p.enabled = true order by p.created_at desc
+  `)
+
+  const sparklines = new Map<string, Array<{ price: number; t: string }>>()
+  for (const r of rows) {
+    const snaps = await db.select({ price: priceSnapshots.price, scrapedAt: priceSnapshots.scrapedAt })
+      .from(priceSnapshots)
+      .where(eq(priceSnapshots.productId, r.id))
+      .orderBy(desc(priceSnapshots.scrapedAt))
+      .limit(30)
+    sparklines.set(r.id, snaps
+      .filter((s) => s.price !== null)
+      .reverse()
+      .map((s) => ({ price: Number(s.price), t: s.scrapedAt.toISOString() })))
+  }
+
+  return (
+    <main className="mx-auto max-w-5xl p-6">
+      <header className="mb-6 flex items-center justify-between">
+        <h1 className="text-2xl font-bold">Preis-Tracker</h1>
+        <div className="flex gap-2">
+          <Link href="/add" className="rounded bg-emerald-600 px-3 py-1.5 text-sm font-medium hover:bg-emerald-500">+ Produkt</Link>
+          <Link href="/api/auth/logout" className="rounded bg-zinc-800 px-3 py-1.5 text-sm hover:bg-zinc-700">Logout</Link>
+        </div>
+      </header>
+      {rows.length === 0 ? (
+        <div className="rounded border border-dashed border-zinc-700 p-12 text-center text-zinc-400">
+          Noch keine Produkte. <Link href="/add" className="text-emerald-400 underline">Erstes hinzufügen</Link>.
+        </div>
+      ) : (
+        <div className="grid grid-cols-1 gap-3 md:grid-cols-2 lg:grid-cols-3">
+          {rows.map((r) => (
+            <ProductCard
+              key={r.id}
+              id={r.id}
+              name={r.name}
+              shop={r.shop}
+              imageUrl={r.image_url}
+              lastPrice={r.last_price}
+              minPrice={r.min_price}
+              sparkline={sparklines.get(r.id) ?? []}
+            />
+          ))}
+        </div>
+      )}
+    </main>
+  )
 }

src/components/ProductCard.tsx

@@ -0,0 +1,37 @@
+import Link from 'next/link'
+import { Sparkline } from './Sparkline'
+
+interface Props {
+  id: string
+  name: string
+  shop: string
+  imageUrl: string | null
+  lastPrice: string | null
+  minPrice: string | null
+  sparkline: Array<{ price: number; t: string }>
+}
+
+export function ProductCard(p: Props) {
+  const last = p.lastPrice ? Number(p.lastPrice) : null
+  const min = p.minPrice ? Number(p.minPrice) : null
+  const deltaFromMin = last !== null && min !== null ? (last - min).toFixed(2) : null
+
+  return (
+    <Link href={`/products/${p.id}`} className="block rounded-lg border border-zinc-800 bg-zinc-900 p-4 hover:border-zinc-700 transition">
+      <div className="flex gap-3">
+        {p.imageUrl && <img src={p.imageUrl} alt="" className="h-16 w-16 object-contain rounded bg-white" />}
+        <div className="flex-1 min-w-0">
+          <div className="text-xs uppercase tracking-wide text-zinc-500">{p.shop}</div>
+          <div className="truncate text-sm font-medium">{p.name}</div>
+          <div className="mt-1 flex items-baseline gap-2">
+            <span className="text-lg font-semibold">{last !== null ? `${last.toFixed(2)} €` : '—'}</span>
+            {deltaFromMin !== null && (
+              <span className="text-xs text-zinc-400">+{deltaFromMin} € vom Tief</span>
+            )}
+          </div>
+        </div>
+      </div>
+      <div className="mt-2"><Sparkline data={p.sparkline} /></div>
+    </Link>
+  )
+}

src/components/Sparkline.tsx

@@ -0,0 +1,14 @@
+'use client'
+import { LineChart, Line, ResponsiveContainer, YAxis } from 'recharts'
+
+export function Sparkline({ data }: { data: Array<{ price: number; t: string }> }) {
+  if (data.length === 0) return <div className="h-10 text-xs text-zinc-500">keine Daten</div>
+  return (
+    <ResponsiveContainer width="100%" height={40}>
+      <LineChart data={data}>
+        <YAxis hide domain={['dataMin', 'dataMax']} />
+        <Line type="monotone" dataKey="price" stroke="#22c55e" strokeWidth={2} dot={false} isAnimationActive={false} />
+      </LineChart>
+    </ResponsiveContainer>
+  )
+}