Add initial backend implementation

- Go module with Gin, GORM, JWT, excelize dependencies
- Configuration loading from YAML with all settings
- GORM models for users, categories, components, configurations, alerts
- Repository layer for all entities
- Services: auth (JWT), pricing (median/average/weighted), components,
  quotes, configurations, export (CSV/XLSX), alerts
- Middleware: JWT auth, role-based access, CORS
- HTTP handlers for all API endpoints
- Main server with dependency injection and graceful shutdown

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/services/component.go

@@ -0,0 +1,187 @@
+package services
+
+import (
+	"strings"
+
+	"github.com/mchus/quoteforge/internal/models"
+	"github.com/mchus/quoteforge/internal/repository"
+)
+
+type ComponentService struct {
+	componentRepo *repository.ComponentRepository
+	categoryRepo  *repository.CategoryRepository
+	statsRepo     *repository.StatsRepository
+}
+
+func NewComponentService(
+	componentRepo *repository.ComponentRepository,
+	categoryRepo *repository.CategoryRepository,
+	statsRepo *repository.StatsRepository,
+) *ComponentService {
+	return &ComponentService{
+		componentRepo: componentRepo,
+		categoryRepo:  categoryRepo,
+		statsRepo:     statsRepo,
+	}
+}
+
+// ParsePartNumber extracts category, vendor, model from lot_name
+// "CPU_AMD_9654" → category="CPU", vendor="AMD", model="9654"
+// "MB_INTEL_4.Sapphire_2S_32xDDR5" → category="MB", vendor="INTEL", model="4.Sapphire_2S_32xDDR5"
+func ParsePartNumber(lotName string) (category, vendor, model string) {
+	parts := strings.SplitN(lotName, "_", 3)
+	if len(parts) >= 1 {
+		category = parts[0]
+	}
+	if len(parts) >= 2 {
+		vendor = parts[1]
+	}
+	if len(parts) >= 3 {
+		model = parts[2]
+	}
+	return
+}
+
+type ComponentListResult struct {
+	Components []ComponentView `json:"components"`
+	Total      int64           `json:"total"`
+	Page       int             `json:"page"`
+	PerPage    int             `json:"per_page"`
+}
+
+type ComponentView struct {
+	LotName         string                  `json:"lot_name"`
+	Description     string                  `json:"description"`
+	Category        string                  `json:"category"`
+	CategoryName    string                  `json:"category_name"`
+	Vendor          string                  `json:"vendor"`
+	Model           string                  `json:"model"`
+	CurrentPrice    *float64                `json:"current_price"`
+	PriceFreshness  models.PriceFreshness   `json:"price_freshness"`
+	PopularityScore float64                 `json:"popularity_score"`
+	Specs           models.Specs            `json:"specs,omitempty"`
+}
+
+func (s *ComponentService) List(filter repository.ComponentFilter, page, perPage int) (*ComponentListResult, error) {
+	if page < 1 {
+		page = 1
+	}
+	if perPage < 1 || perPage > 100 {
+		perPage = 20
+	}
+	offset := (page - 1) * perPage
+
+	components, total, err := s.componentRepo.List(filter, offset, perPage)
+	if err != nil {
+		return nil, err
+	}
+
+	views := make([]ComponentView, len(components))
+	for i, c := range components {
+		view := ComponentView{
+			LotName:         c.LotName,
+			Vendor:          c.Vendor,
+			Model:           c.Model,
+			CurrentPrice:    c.CurrentPrice,
+			PriceFreshness:  c.GetPriceFreshness(30, 60, 90, 3),
+			PopularityScore: c.PopularityScore,
+			Specs:           c.Specs,
+		}
+
+		if c.Lot != nil {
+			view.Description = c.Lot.LotDescription
+		}
+		if c.Category != nil {
+			view.Category = c.Category.Code
+			view.CategoryName = c.Category.Name
+		}
+
+		views[i] = view
+	}
+
+	return &ComponentListResult{
+		Components: views,
+		Total:      total,
+		Page:       page,
+		PerPage:    perPage,
+	}, nil
+}
+
+func (s *ComponentService) GetByLotName(lotName string) (*ComponentView, error) {
+	c, err := s.componentRepo.GetByLotName(lotName)
+	if err != nil {
+		return nil, err
+	}
+
+	// Track usage
+	_ = s.componentRepo.IncrementRequestCount(lotName)
+
+	view := &ComponentView{
+		LotName:         c.LotName,
+		Vendor:          c.Vendor,
+		Model:           c.Model,
+		CurrentPrice:    c.CurrentPrice,
+		PriceFreshness:  c.GetPriceFreshness(30, 60, 90, 3),
+		PopularityScore: c.PopularityScore,
+		Specs:           c.Specs,
+	}
+
+	if c.Lot != nil {
+		view.Description = c.Lot.LotDescription
+	}
+	if c.Category != nil {
+		view.Category = c.Category.Code
+		view.CategoryName = c.Category.Name
+	}
+
+	return view, nil
+}
+
+func (s *ComponentService) GetCategories() ([]models.Category, error) {
+	return s.categoryRepo.GetAll()
+}
+
+func (s *ComponentService) GetVendors(category string) ([]string, error) {
+	return s.componentRepo.GetVendors(category)
+}
+
+// ImportFromLot creates metadata entries for lots that don't have them
+func (s *ComponentService) ImportFromLot() (int, error) {
+	lots, err := s.componentRepo.GetLotsWithoutMetadata()
+	if err != nil {
+		return 0, err
+	}
+
+	categories, err := s.categoryRepo.GetAll()
+	if err != nil {
+		return 0, err
+	}
+
+	categoryMap := make(map[string]uint)
+	for _, cat := range categories {
+		categoryMap[cat.Code] = cat.ID
+	}
+
+	imported := 0
+	for _, lot := range lots {
+		category, vendor, model := ParsePartNumber(lot.LotName)
+
+		metadata := &models.LotMetadata{
+			LotName: lot.LotName,
+			Vendor:  vendor,
+			Model:   model,
+			Specs:   make(models.Specs),
+		}
+
+		if catID, ok := categoryMap[category]; ok {
+			metadata.CategoryID = &catID
+		}
+
+		if err := s.componentRepo.Create(metadata); err != nil {
+			continue
+		}
+		imported++
+	}
+
+	return imported, nil
+}