Add progress overlay to AI Catalog Price Check

Shows a modal overlay with animated progress bar and batch-aware status messages
while Claude is analyzing. Progress animates in two phases: ease-out to ~85%
over the estimated duration, then a slow crawl to 99% so it never falsely
"completes" before the server responds.

- Overlay driven by CSS (hidden until .active added by JS)
- Item count passed from controller as data-item-count on the run button
- Batch count derived from item count (batches of 25) to show accurate
  "Analyzing batch N of M…" messages

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

src/PowderCoating.Web/Controllers/CatalogItemsController.cs

@@ -938,6 +938,9 @@ namespace PowderCoating.Web.Controllers
                 r => r.CompanyId == currentUser.CompanyId);
             var report = existing.OrderByDescending(r => r.RunAt).FirstOrDefault();
 
+            var activeItems = await _unitOfWork.CatalogItems.FindAsync(ci => ci.IsActive);
+            ViewBag.ActiveItemCount = activeItems.Count();
+
             CatalogPriceCheckReportDto? dto = null;
             if (report != null)
             {