Add inventory bin filter, print bin, mobile login fixes, and QR scan fix

- Inventory: location filter dropdown + Print Bin page (line #, name, color, SKU)
- Fix: Prismatic Powders QR scan now extracts manufacturer/SKU/color from URL path
  and uses full LookupAsync pipeline instead of relying on page fetch alone
- Fix: iOS Safari 'Login / data Zero KB' download -- add OnRejected HTML response to rate limiter
- Fix: mobile session logout -- ConfigureApplicationCookie with 30-day MaxAge persistent cookie
- Help: new 'Location Filtering & Bin Print' section in Inventory help article
- Help: HelpKnowledgeBase updated with bin filter and print bin details

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

src/PowderCoating.Infrastructure/Services/InventoryAiLookupService.cs

@@ -1209,6 +1209,15 @@ Rules:
             sb.AppendLine("Page content:");
             sb.AppendLine(pageContent);
         }
+        else if (!string.IsNullOrWhiteSpace(fetchUrl))
+        {
+            // Page content unavailable (fetch failed or blocked) — still surface the URL so Claude
+            // can use its training knowledge of the manufacturer URL structure (e.g. Prismatic SKU
+            // in the path) to infer product identity rather than returning all-null fields.
+            sb.AppendLine();
+            sb.AppendLine($"Product URL (page content could not be fetched): {fetchUrl}");
+            sb.AppendLine("Use your training knowledge of this manufacturer and the URL to fill in as many fields as possible.");
+        }
 
         return sb.ToString();
     }