feat: implement vendor spec BOM import and PN→LOT resolution (Phase 1)

- Migration 029: local_partnumber_books, local_partnumber_book_items,
  vendor_spec TEXT column on local_configurations
- Models: LocalPartnumberBook, LocalPartnumberBookItem, VendorSpec,
  VendorSpecItem with JSON Valuer/Scanner
- Repository: PartnumberBookRepository (GetActiveBook, FindLotByPartnumber,
  SaveBook/Items, ListBooks, CountBookItems)
- Service: VendorSpecResolver 3-step resolution (book → manual suggestion
  → unresolved) + AggregateLOTs with is_primary_pn qty logic
- Sync: PullPartnumberBooks append-only pull from qt_partnumber_books
- Handlers: VendorSpecHandler (GET/PUT/resolve/apply), PartnumberBooksHandler
- Routes: /api/configs/:uuid/vendor-spec*, /api/partnumber-books,
  /api/sync/partnumber-books, /partnumber-books page
- UI: 3 top-level tabs [Estimate][BOM вендора][Ценообразование]; Excel paste,
  PN resolution, inline LOT autocomplete, pricing table
- Bible: 03-database.md updated, 09-vendor-spec.md added

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

internal/handlers/partnumber_books.go

@@ -0,0 +1,90 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+
+	"git.mchus.pro/mchus/quoteforge/internal/localdb"
+	"git.mchus.pro/mchus/quoteforge/internal/repository"
+	"github.com/gin-gonic/gin"
+)
+
+// PartnumberBooksHandler provides read-only access to local partnumber book snapshots.
+type PartnumberBooksHandler struct {
+	localDB *localdb.LocalDB
+}
+
+func NewPartnumberBooksHandler(localDB *localdb.LocalDB) *PartnumberBooksHandler {
+	return &PartnumberBooksHandler{localDB: localDB}
+}
+
+// List returns all local partnumber book snapshots.
+// GET /api/partnumber-books
+func (h *PartnumberBooksHandler) List(c *gin.Context) {
+	bookRepo := repository.NewPartnumberBookRepository(h.localDB.DB())
+	books, err := bookRepo.ListBooks()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	type bookSummary struct {
+		ID        uint   `json:"id"`
+		ServerID  int    `json:"server_id"`
+		Version   string `json:"version"`
+		CreatedAt string `json:"created_at"`
+		IsActive  bool   `json:"is_active"`
+		ItemCount int64  `json:"item_count"`
+	}
+
+	summaries := make([]bookSummary, 0, len(books))
+	for _, b := range books {
+		summaries = append(summaries, bookSummary{
+			ID:        b.ID,
+			ServerID:  b.ServerID,
+			Version:   b.Version,
+			CreatedAt: b.CreatedAt.Format("2006-01-02"),
+			IsActive:  b.IsActive,
+			ItemCount: bookRepo.CountBookItems(b.ID),
+		})
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"books": summaries,
+		"total": len(summaries),
+	})
+}
+
+// GetItems returns items for a partnumber book by server ID.
+// GET /api/partnumber-books/:id
+func (h *PartnumberBooksHandler) GetItems(c *gin.Context) {
+	idStr := c.Param("id")
+	id, err := strconv.ParseUint(idStr, 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid book ID"})
+		return
+	}
+
+	bookRepo := repository.NewPartnumberBookRepository(h.localDB.DB())
+
+	// Find local book by server_id
+	var book localdb.LocalPartnumberBook
+	if err := h.localDB.DB().Where("server_id = ?", id).First(&book).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "partnumber book not found"})
+		return
+	}
+
+	items, err := bookRepo.GetBookItems(book.ID)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"book_id":   book.ServerID,
+		"version":   book.Version,
+		"is_active": book.IsActive,
+		"items":     items,
+		"total":     len(items),
+	})
+}