feat(vendor-spec): BOM import, LOT autocomplete, pricing, partnumber_seen push

- BOM paste: auto-detect columns by content (price, qty, PN, description);
  handles $5,114.00 and European comma-decimal formats
- LOT input: HTML5 datalist rebuilt on each renderBOMTable from allComponents;
  oninput updates data only (no re-render), onchange validates+resolves
- BOM persistence: PUT handler explicitly marshals VendorSpec to JSON string
  (GORM Update does not reliably call driver.Valuer for custom types)
- BOM autosave after every resolveBOM() call
- Pricing tab: async renderPricingTab() calls /api/quote/price-levels for all
  resolved LOTs directly — Estimate prices shown even before cart apply
- Unresolved PNs pushed to qt_vendor_partnumber_seen via POST
  /api/sync/partnumber-seen (fire-and-forget from JS)
- sync.PushPartnumberSeen(): upsert with ON DUPLICATE KEY UPDATE last_seen_at
- partnumber_books: pull ALL books (not only is_active=1); re-pull items when
  header exists but item count is 0; fallback for missing description column
- partnumber_books UI: collapsible snapshot section (collapsed by default),
  pagination (10/page), sync button always visible in header
- vendorSpec handlers: use GetConfigurationByUUID + IsActive check (removed
  original_username from WHERE — GetUsername returns "" without JWT)
- bible/09-vendor-spec.md: updated with all architectural decisions

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

internal/handlers/sync.go

@@ -679,3 +679,35 @@ func (h *SyncHandler) getReadinessCached(maxAge time.Duration) *sync.SyncReadine
 	h.readinessMu.Unlock()
 	return readiness
 }
+
+// ReportPartnumberSeen pushes unresolved vendor partnumbers to qt_vendor_partnumber_seen on MariaDB.
+// POST /api/sync/partnumber-seen
+func (h *SyncHandler) ReportPartnumberSeen(c *gin.Context) {
+	var body struct {
+		Items []struct {
+			Partnumber  string `json:"partnumber"`
+			Description string `json:"description"`
+		} `json:"items"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	items := make([]sync.SeenPartnumber, 0, len(body.Items))
+	for _, it := range body.Items {
+		if it.Partnumber != "" {
+			items = append(items, sync.SeenPartnumber{
+				Partnumber:  it.Partnumber,
+				Description: it.Description,
+			})
+		}
+	}
+
+	if err := h.syncService.PushPartnumberSeen(items); err != nil {
+		c.JSON(http.StatusServiceUnavailable, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{"reported": len(items)})
+}