feat(business): add Business section with Markup pricing v1.28.0
- Add business_settings table for Markup configuration
- Add product_sheets table for product technical sheets (CMV)
- Add product_sheet_items table for cost components
- Create BusinessSetting model with calculateMarkup() method
- Create ProductSheet model with recalculateCmv() method
- Create ProductSheetItem model for cost breakdown
- Add BusinessSettingController with CRUD + simulate-price endpoint
- Add ProductSheetController with CRUD + items management + duplicate
- Add Business page with 3 tabs (Settings, Products, Calculator)
- Add BusinessSettingsTab component with markup cards
- Add ProductSheetsTab component with product grid
- Add PriceCalculatorTab component with interactive simulator
- Add i18n translations in ES, PT-BR, EN
- Multi-currency support (EUR, BRL, USD)
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