feat: Studio UI (upload/recipe/submit island) + queue view + library/file API

- StudioApp.tsx: upload (file/DnD/paste, HEIC, to /api/uploads), combinable task
  toggles with validation (contour needs cutout, freistellen+theframe blocked),
  format+orientation+live px+crop, contour mm, custom instruction, delivery, recipe prefill
- QueueApp.tsx + warteschlange.astro: live polling, progress+ETA, per-item status,
  retry/pause/resume/cancel, result thumbnails+download
- api/items (library filters), api/items/:id/file (stream result/source from S3)
- index.astro renders Studio island

src/pages/index.astro

@@ -1,21 +1,9 @@
 ---
 import Base from '../layouts/Base.astro';
-const user = Astro.locals.user!;
+import StudioApp from '../components/StudioApp.tsx';
+import { query } from '../lib/db';
+const recipes = await query('SELECT * FROM recipes ORDER BY is_default DESC, name').catch(() => []);
 ---
 <Base title="Studio · Klarbild">
-  <section>
-    <h1 class="display">Studio</h1>
-    <p class="lead">Willkommen, {user.name}. Ziehe Screenshots herein, wähle ein Rezept — Klarbild macht daraus druckfertige Bilder.</p>
-    <div class="soon card">
-      <strong>Aufbau läuft.</strong>
-      <p>Das Fundament steht (Login, Datenbank, Objektspeicher, Health). Als Nächstes: Upload, Rezepte, Warteschlange und die Bildpipeline.</p>
-    </div>
-  </section>
-  <style>
-    .display { font-family: var(--font-display); font-size: 2rem; margin: 8px 0 6px; letter-spacing: -0.02em; }
-    .lead { color: var(--ink-soft); max-width: 60ch; }
-    .card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
-      padding: 20px; box-shadow: var(--shadow); margin-top: 20px; max-width: 60ch; }
-    .card p { color: var(--ink-mute); margin: 6px 0 0; }
-  </style>
+  <StudioApp client:load recipes={recipes} />
 </Base>