feat: automatische Content-Pipeline (release → pairs → übersetzen → audio → ready)

- pictures.pipeline_* Spalten + app_settings Tabelle (Migration)
- lib/placeholders.js: Placeholder-Auflösung; TTS spricht keine UUIDs mehr
- lib/pairContent.js: geteilte Pair-Logik (Readiness mit Skip-Optionen)
- lib/generatePairs.js: Claude-Generierung (konfigurierbare Anzahl, nur
  Nomen/Adjektive bei word-Pairs) + serverseitige Persistenz inkl. object_pairs
- lib/pipeline.js: In-Process-Runner, idempotente Schritte, Boot-Resume
- routes/pipeline.js: release/retry/overview/bundle/settings + Bild-Publish
  (kaskadiert Fragen/Statements/Pairs/Wörter/Objekte/Bild)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/db-migrate.js

@@ -603,6 +603,38 @@ async function migrate() {
     ON CONFLICT (language) DO NOTHING
   `).catch(() => {});
 
+  // ── Content-Pipeline: Job-Tracking direkt auf der Picture-Zeile ──────────────
+  await query(`ALTER TABLE pictures ADD COLUMN IF NOT EXISTS pipeline_status TEXT NOT NULL DEFAULT 'none'`).catch(() => {});
+  await query(`ALTER TABLE pictures DROP CONSTRAINT IF EXISTS pictures_pipeline_status_check`).catch(() => {});
+  await query(`
+    ALTER TABLE pictures ADD CONSTRAINT pictures_pipeline_status_check
+    CHECK (pipeline_status IN ('none', 'queued', 'running', 'failed', 'ready', 'published'))
+  `).catch(() => {});
+  await query(`ALTER TABLE pictures ADD COLUMN IF NOT EXISTS pipeline_step        TEXT`).catch(() => {});
+  await query(`ALTER TABLE pictures ADD COLUMN IF NOT EXISTS pipeline_progress    JSONB`).catch(() => {});
+  await query(`ALTER TABLE pictures ADD COLUMN IF NOT EXISTS pipeline_error       TEXT`).catch(() => {});
+  await query(`ALTER TABLE pictures ADD COLUMN IF NOT EXISTS pipeline_started_at  TIMESTAMPTZ`).catch(() => {});
+  await query(`ALTER TABLE pictures ADD COLUMN IF NOT EXISTS pipeline_finished_at TIMESTAMPTZ`).catch(() => {});
+
+  // app_settings — generischer Key/Value-Store (JSONB) für Konfiguration
+  await query(`
+    CREATE TABLE IF NOT EXISTS app_settings (
+      key        TEXT        PRIMARY KEY,
+      value      JSONB       NOT NULL,
+      updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+    )
+  `);
+  await query(`
+    DROP TRIGGER IF EXISTS app_settings_updated_at ON app_settings;
+    CREATE TRIGGER app_settings_updated_at
+      BEFORE UPDATE ON app_settings
+      FOR EACH ROW EXECUTE FUNCTION update_updated_at()
+  `);
+  await query(`
+    INSERT INTO app_settings (key, value) VALUES ('pipeline.pairs_per_object', '5'::jsonb)
+    ON CONFLICT (key) DO NOTHING
+  `).catch(() => {});
+
   // ── Migrate old {{uuid}} placeholders → new {{label.w:uuid}} / {{label.o:uuid}} ──
   await migratePlaceholders();