feat: Legal Templates — Attribution-Tracking + 6 neue Templates (DE/EN)

Migration 019: 5 neue Herkunftsspalten (source_url, source_repo,
source_file_path, source_retrieved_at, attribution_text, inspiration_sources)
ermöglichen lückenlosen Nachweis jeder Template-Quelle.

Neue Templates:
  DE: AVV (Art. 28 DSGVO), Widerrufsbelehrung (EGBGB Anlage 1, §5 UrhG),
      Cookie-Richtlinie (TTDSG §25)
  EN: Privacy Policy (GDPR), Terms of Service (EU Directive 2011/83),
      Data Processing Agreement (GDPR Art. 28)

Gesamt: 9 Templates — 5 DE, 4 EN | 6 document_type-Werte

- VALID_DOCUMENT_TYPES um 3 neue Typen erweitert
- Create/Update-Schemas: attribution fields ergänzt
- Status-Endpoint: alle 6 Typen in by_type
- Tests: 34/34 — alle grün

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/apply_legal_templates_attribution_migration.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+set -e
+echo "Applying Migration 019: Legal Templates Attribution + 6 new templates..."
+/usr/local/bin/docker exec bp-compliance-backend python3 -c "
+import psycopg2, os
+conn = psycopg2.connect(os.getenv('DATABASE_URL'))
+cur = conn.cursor()
+with open('/app/migrations/019_legal_templates_attribution.sql') as f:
+    cur.execute(f.read())
+conn.commit()
+cur.close()
+conn.close()
+print('Migration 019 applied successfully')
+"
+echo "Done."