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/sync.go

@@ -243,6 +243,33 @@ func (h *SyncHandler) SyncPricelists(c *gin.Context) {
 	h.syncService.RecordSyncHeartbeat()
 }
 
+// SyncPartnumberBooks syncs partnumber book snapshots from MariaDB to local SQLite.
+// POST /api/sync/partnumber-books
+func (h *SyncHandler) SyncPartnumberBooks(c *gin.Context) {
+	if !h.ensureSyncReadiness(c) {
+		return
+	}
+
+	startTime := time.Now()
+	pulled, err := h.syncService.PullPartnumberBooks()
+	if err != nil {
+		slog.Error("partnumber books pull failed", "error", err)
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"success": false,
+			"error":   err.Error(),
+		})
+		return
+	}
+
+	c.JSON(http.StatusOK, SyncResultResponse{
+		Success:  true,
+		Message:  "Partnumber books synced successfully",
+		Synced:   pulled,
+		Duration: time.Since(startTime).String(),
+	})
+	h.syncService.RecordSyncHeartbeat()
+}
+
 // SyncAllResponse represents result of full sync
 type SyncAllResponse struct {
 	Success                bool   `json:"success"`