feat: reviewed-Status für Bilder, Auto-Trigger, Übersetzungen, Vertonbarkeits-Regel

- pictures: reviewed-Status (Constraint + ALLOWED_STATUSES + Auto-Trigger beim Object-Linking)
- objects: STATUSES um reviewed erweitert; Auto-Trigger draft→reviewed wenn Pair verlinkt
- pairs/statements/questions: STATUSES um reviewed (Phase-1-Lücke)
- pairs: POST /:id/review kaskadiert Pair+Frage+Statements (verlangt alle 3 Sprachen)
- words: Auto requested→translated wenn alle titel_* gefüllt (POST+PATCH)
- audios computeUnits: nur vertonbar wenn ALLE 3 Sprachen pro Feld gefüllt
- claude: translate-text/translate-row/translate-missing mit Placeholder-Schutz
  (⟦PHn:label⟧-Tokenisierung, Label übersetzt, UUID erhalten); translation-coverage

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/db-migrate.js

@@ -17,7 +17,7 @@ async function migrate() {
     CREATE TABLE IF NOT EXISTS pictures (
       id                      UUID PRIMARY KEY DEFAULT gen_random_uuid(),
       status                  VARCHAR(20)  NOT NULL DEFAULT 'uploaded'
-                                CHECK (status IN ('uploaded', 'published', 'blocked')),
+                                CHECK (status IN ('uploaded', 'reviewed', 'published', 'blocked')),
       blocked_reason          VARCHAR(20)  CHECK (blocked_reason IN ('regenerate', 'not_to_use')),
       generation_prompt       TEXT,
       generation_timestamp    TIMESTAMPTZ,
@@ -39,6 +39,9 @@ async function migrate() {
     $$ LANGUAGE plpgsql
   `);
 
+  await query(`ALTER TABLE pictures DROP CONSTRAINT IF EXISTS pictures_status_check`).catch(() => {});
+  await query(`ALTER TABLE pictures ADD CONSTRAINT pictures_status_check CHECK (status IN ('uploaded', 'reviewed', 'published', 'blocked'))`).catch(() => {});
+
   await query(`
     DROP TRIGGER IF EXISTS pictures_updated_at ON pictures;
     CREATE TRIGGER pictures_updated_at