feat: material alias seeds expansion, bulk product delete, dashboard stats widgets
- Material alias seeds: 95 → 855 aliases covering German variants, DIN standards,
Werkstoffnummern, industry terms, English equivalents, polymer abbreviations
- Batch product delete/deactivate endpoint (POST /products/batch-delete)
- Multi-select UI on Products page with floating action bar
- Dashboard: RenderThroughput + MaterialCoverage widgets
- Dashboard stats endpoint (GET /admin/dashboard-stats)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Hartmut
f0dd952f63