feat: image core — format math, sharp pipeline, sticker contour, prompts, pg-boss queue+worker

- format.ts: exact px (cm/2.54*dpi), catalog incl. The Frame/portrait, aspect ratio
- pipeline.ts: finalizeToFormat (cover/attention crop, dpi metadata), stickerContour
  (alpha dilation -> white border), heic->png, german filename slug
- prompts.ts: task prompts (clean/cutout/format) — reproduce, don't reinterpret
- process.ts: per-item chain (load -> model /v1/images -> finalize -> contour -> store)
- queue.ts + worker.ts: pg-boss (concurrency, retry, counters, 402 pause, completion)
- verified locally: 30x40@300dpi = exact 3543x4724 + dpi meta; sticker white border + alpha

src/worker.ts

@@ -0,0 +1,58 @@
+import { one, query } from './lib/db';
+import { startWorker, type GenerateJob } from './lib/queue';
+import { processItem } from './lib/process';
+
+/** Startet den Warteschlangen-Arbeiter (im selben Node-Prozess wie die App). */
+export async function startImageWorker(): Promise<void> {
+  const s = await one<{ concurrency: number }>('SELECT concurrency FROM settings WHERE id=1');
+  const concurrency = s?.concurrency ?? 2;
+  await startWorker(concurrency, handle);
+}
+
+async function handle(job: GenerateJob): Promise<void> {
+  // Angehaltene/abgebrochene Aufträge nicht verarbeiten.
+  const j = await one<{ status: string }>('SELECT status FROM jobs WHERE id=$1', [job.jobId]);
+  if (!j || j.status === 'paused' || j.status === 'cancelled') {
+    await query(`UPDATE items SET status='queued' WHERE id=$1 AND status='running'`, [job.itemId]);
+    return;
+  }
+  await query(`UPDATE jobs SET status='running' WHERE id=$1 AND status='queued'`, [job.jobId]);
+
+  try {
+    const res = await processItem(job.itemId);
+    if (res.ok) {
+      await query(`UPDATE jobs SET done_count=done_count+1 WHERE id=$1`, [job.jobId]);
+    } else {
+      await query(`UPDATE jobs SET failed_count=failed_count+1 WHERE id=$1`, [job.jobId]);
+    }
+  } catch (e: any) {
+    if (e?.status === 402) {
+      // Guthaben erschöpft → Auftrag anhalten, Position zurück in die Schlange.
+      await query(`UPDATE jobs SET status='paused' WHERE id=$1`, [job.jobId]);
+      await query(`UPDATE items SET status='queued', error_message='Guthaben erschöpft' WHERE id=$1`,
+        [job.itemId]);
+      console.error('[worker] 402 — Auftrag angehalten', job.jobId);
+      return;
+    }
+    await query(`UPDATE items SET status='failed', error_message=$2 WHERE id=$1`,
+      [job.itemId, String(e?.message || e).slice(0, 500)]);
+    await query(`UPDATE jobs SET failed_count=failed_count+1 WHERE id=$1`, [job.jobId]);
+  }
+
+  await maybeComplete(job.jobId);
+}
+
+/** Auftrag abschließen, wenn alle Positionen fertig/fehlgeschlagen sind. */
+async function maybeComplete(jobId: string): Promise<void> {
+  const row = await one<{ total: number; done: number; failed: number; open: number }>(
+    `SELECT total,
+       (SELECT count(*) FROM items WHERE job_id=$1 AND status='done')::int AS done,
+       (SELECT count(*) FROM items WHERE job_id=$1 AND status='failed')::int AS failed,
+       (SELECT count(*) FROM items WHERE job_id=$1 AND status IN ('queued','running'))::int AS open
+     FROM jobs WHERE id=$1`, [jobId]);
+  if (row && row.open === 0) {
+    await query(`UPDATE jobs SET status='done', finished_at=now() WHERE id=$1 AND status<>'cancelled'`,
+      [jobId]);
+    // TODO: Auslieferung (Picdrop) + Benachrichtigung (Telegram/n8n) anstoßen.
+  }
+}