Bulk multi-select actions, barcode format, batch printing, site name on login

Multi-select (Ctrl/Cmd+click toggle, Shift+click range, right-click the
active selection for bulk actions - same conventions as a native file
manager):
- Print Labels (N) / Export CSV (N) for any mix of individually-picked
  assets and whole folders. Labels/export now take asset_ids/folder_ids
  instead of a single asset_id/folder_id.
- Edit Status..., Check Out..., Duplicate, Move to..., and Delete, bulk
  versions of the existing single-asset actions. Checkout/Move modals
  were generalized to accept an array of ids instead of just one; status
  editing got its own lightweight POST /app/assets/{id}/status endpoint
  (assets.SetStatus) so a bulk status change doesn't need to resend every
  other field the way a full PATCH would.

Labels:
- Choose QR (a /scan/<tag> URL, for a phone camera) or Code128 barcode
  (the bare Asset ID, for a USB scanner typing into the search box) via a
  format selector on the print page. New barcodeDataURI using
  github.com/boombuler/barcode alongside the existing QR generator.
- "Start at #" lets printing resume partway into an already-used sheet
  instead of wasting it on a fresh one.
- Added the Avery 5260 label template (same grid as 5160, rounded
  corners, so it isn't flagged approximate).

Also: the configured Site Name now shows on the login page too, not just
the authenticated navbar.

internal/web/handlers_csv.go

@@ -10,6 +10,41 @@ import (
 
 func (a *App) handleExportCSV(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
+	filename := fmt.Sprintf("inventree-assets-%s.csv", time.Now().Format("2006-01-02"))
+	w.Header().Set("Content-Type", "text/csv; charset=utf-8")
+	w.Header().Set("Content-Disposition", "attachment; filename=\""+filename+"\"")
+
+	assetIDsParam := r.URL.Query().Get("asset_ids")
+	folderIDsParam := r.URL.Query().Get("folder_ids")
+	if assetIDsParam != "" || folderIDsParam != "" {
+		// A multi-select batch (an arbitrary mix of individually-picked
+		// assets and whole folders) doesn't map onto a single ListFilter.
+		seen := map[int64]bool{}
+		var ids []int64
+		for _, id := range parseIDList(assetIDsParam) {
+			if !seen[id] {
+				seen[id] = true
+				ids = append(ids, id)
+			}
+		}
+		for _, fid := range parseIDList(folderIDsParam) {
+			batch, _, err := a.Assets.List(ctx, assets.ListFilter{FolderID: &fid, FolderSet: true, IncludeSub: true, Page: 1, PageSize: 2000})
+			if err != nil {
+				continue
+			}
+			for _, as := range batch {
+				if !seen[as.ID] {
+					seen[as.ID] = true
+					ids = append(ids, as.ID)
+				}
+			}
+		}
+		if err := a.Assets.ExportByIDs(ctx, w, ids); err != nil {
+			a.Log.Error("csv export failed", "error", err)
+		}
+		return
+	}
+
 	filter := assets.ListFilter{
 		ItemTypeID:     queryInt64(r, "item_type_id"),
 		StatusID:       queryInt64(r, "status_id"),
@@ -21,10 +56,6 @@ func (a *App) handleExportCSV(w http.ResponseWriter, r *http.Request) {
 		filter.FolderSet = true
 		filter.IncludeSub = r.URL.Query().Get("recursive") == "1"
 	}
-
-	filename := fmt.Sprintf("inventree-assets-%s.csv", time.Now().Format("2006-01-02"))
-	w.Header().Set("Content-Type", "text/csv; charset=utf-8")
-	w.Header().Set("Content-Disposition", "attachment; filename=\""+filename+"\"")
 	if err := a.Assets.Export(ctx, w, filter); err != nil {
 		a.Log.Error("csv export failed", "error", err)
 	}