feat: add VAT tax rate, cost, and Letzshop feed settings
Product Model:
- Add tax_rate_percent (NOT NULL, default 17) for Luxembourg VAT
- Add cost_cents for profit calculation
- Add profit calculation properties: net_price, vat_amount, profit, margin
- Rename supplier_cost_cents to cost_cents
MarketplaceProduct Model:
- Add tax_rate_percent (NOT NULL, default 17)
Vendor Model (Letzshop feed settings):
- letzshop_default_tax_rate: Default VAT for new products (0, 3, 8, 14, 17)
- letzshop_boost_sort: Product sort priority (0.0-10.0)
- letzshop_delivery_method: nationwide, package_delivery, self_collect
- letzshop_preorder_days: Pre-order shipping delay
VAT Strategy:
- Store prices as gross (VAT-inclusive) for B2C
- Calculate net from gross when needed for profit
- Luxembourg VAT rates: 0%, 3%, 8%, 14%, 17%
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Samir Boulahtit
8a2a955c92