feat: Bibliothek + Admin

- Bibliothek: grid, before/after slider, rename, download, folder assign, delete, multi-select
- Admin: stats+costs, OpenRouter key (masked/encrypted), budget, defaults, Picdrop config+test,
  models (list/add from OpenRouter/set default/delete), users (add/set password)
- api: items/:id PATCH+DELETE, folders CRUD, admin/{settings,stats,models,test-picdrop,users}
- lib/picdrop.ts (SFTP/FTPS test+upload, temp->rename)

src/pages/api/admin/stats.ts

@@ -0,0 +1,25 @@
+import type { APIRoute } from 'astro';
+import { query, one } from '../../../lib/db';
+
+export const prerender = false;
+
+export const GET: APIRoute = async () => {
+  const total = await one<{ n: string }>(`SELECT count(*)::text n FROM items WHERE status='done'`);
+  const failed = await one<{ n: string }>(`SELECT count(*)::text n FROM items WHERE status='failed'`);
+  const cost = async (days: number | null) => (await one<{ c: string }>(
+    `SELECT COALESCE(sum(cost),0)::text c FROM items WHERE cost IS NOT NULL` +
+    (days ? ` AND created_at > now() - interval '${days} days'` : ''))
+  )?.c || '0';
+  const byModel = await query(`SELECT COALESCE(model_used,'—') m, count(*)::int n, COALESCE(sum(cost),0)::float c
+    FROM items WHERE status='done' GROUP BY 1 ORDER BY n DESC`);
+  const last = await one<{ t: string }>(`SELECT max(created_at)::text t FROM items`);
+
+  const totalN = Number(total?.n || 0), failedN = Number(failed?.n || 0);
+  return new Response(JSON.stringify({
+    total: totalN, failed: failedN,
+    error_rate: totalN + failedN ? Math.round((failedN / (totalN + failedN)) * 100) : 0,
+    cost_today: Number(await cost(1)), cost_7: Number(await cost(7)),
+    cost_30: Number(await cost(30)), cost_all: Number(await cost(null)),
+    by_model: byModel, last_activity: last?.t || null,
+  }), { headers: { 'Content-Type': 'application/json' } });
+};