Add PWA manifest, fix AI multi-coat pricing, and improve catalog lookup

- PWA: manifest.json + minimal service worker so iOS/Android persist camera
  permission after "Add to Home Screen"; theme-color and apple meta tags in layout
- PWA icons: 192x192 and 512x512 from transparent PCL logo; updated pcl-logo.png
- AI pricing: apply AdditionalCoatLaborPercent per extra coat on AI items,
  matching the calculated-item path (was ignoring extra coats entirely)
- AI wizard: live price recalc when coats are added/removed; session-expiry
  errors now show a clear "refresh and sign in" message instead of raw HTTP status;
  smooth-scroll to follow-up/results sections on AI response
- Catalog lookup: exclude SKUs already in company inventory from results;
  pass currentId on edit so own entry still appears; vendor-scoped search
  with cross-vendor fallback; result count shown in multi-match modal

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

src/PowderCoating.Web/Controllers/InventoryController.cs

@@ -1029,12 +1029,13 @@ public class InventoryController : Controller
     }
 
     /// <summary>
-    /// Searches the platform-level PowderCatalogItems table by SKU or color name and returns
-    /// up to 10 matches as JSON. Called by the inventory Create/Edit form before falling back
-    /// to the AI Lookup, avoiding unnecessary API calls for known products.
+    /// Searches the platform-level PowderCatalogItems table by SKU or color name.
+    /// Excludes catalog entries already present in the company's inventory (by ManufacturerPartNumber).
+    /// Pass currentId when editing an existing item so its own catalog entry is not filtered out.
+    /// Called by the inventory Create/Edit form before falling back to AI Lookup.
     /// </summary>
     [HttpGet]
-    public async Task<IActionResult> CatalogLookup(string? q, string? vendor)
+    public async Task<IActionResult> CatalogLookup(string? q, string? vendor, int? currentId = null)
     {
         if (string.IsNullOrWhiteSpace(q) || q.Length < 2)
             return Json(Array.Empty<object>());
@@ -1042,18 +1043,47 @@ public class InventoryController : Controller
         var term       = q.Trim().ToLower();
         var vendorTerm = vendor?.Trim().ToLower();
 
-        var matches = await _unitOfWork.PowderCatalog.FindAsync(p =>
-            p.Sku.ToLower() == term ||
-            p.ColorName.ToLower().Contains(term) ||
-            p.Sku.ToLower().Contains(term));
+        // Build a set of SKUs already in this company's inventory so we can exclude them.
+        // When editing, the current item's own SKU is re-included so its catalog entry still appears.
+        var existingItems = await _unitOfWork.InventoryItems.GetAllAsync();
+        var existingSkus = existingItems
+            .Where(i => !string.IsNullOrWhiteSpace(i.ManufacturerPartNumber) && i.Id != (currentId ?? 0))
+            .Select(i => i.ManufacturerPartNumber!.Trim().ToLower())
+            .ToHashSet();
+
+        // When a vendor is specified, search vendor-scoped first. Only widen to all vendors
+        // if the scoped search returns nothing — prevents a cross-vendor color match from
+        // being returned as the only result when the user clearly intended a specific manufacturer.
+        IEnumerable<PowderCatalogItem> matches;
+        if (!string.IsNullOrEmpty(vendorTerm))
+        {
+            matches = await _unitOfWork.PowderCatalog.FindAsync(p =>
+                p.VendorName.ToLower().Contains(vendorTerm) && (
+                    p.Sku.ToLower() == term ||
+                    p.ColorName.ToLower().Contains(term) ||
+                    p.Sku.ToLower().Contains(term)));
+
+            // Fall back to all vendors only when the scoped search finds nothing
+            if (!matches.Any())
+            {
+                matches = await _unitOfWork.PowderCatalog.FindAsync(p =>
+                    p.Sku.ToLower() == term ||
+                    p.ColorName.ToLower().Contains(term) ||
+                    p.Sku.ToLower().Contains(term));
+            }
+        }
+        else
+        {
+            matches = await _unitOfWork.PowderCatalog.FindAsync(p =>
+                p.Sku.ToLower() == term ||
+                p.ColorName.ToLower().Contains(term) ||
+                p.Sku.ToLower().Contains(term));
+        }
 
-        // When a vendor hint is provided, prefer records where VendorName matches,
-        // then fall back to all results so the user still sees cross-vendor options.
         var results = matches
+            .Where(p => !existingSkus.Contains(p.Sku.ToLower()))
             .OrderBy(p => p.Sku.ToLower() == term ? 0 : 1)
-            .ThenBy(p => !string.IsNullOrEmpty(vendorTerm) && p.VendorName.ToLower().Contains(vendorTerm) ? 0 : 1)
             .ThenBy(p => p.ColorName)
-            .Take(10)
             .Select(p => new
             {
                 id = p.Id,
@@ -1075,7 +1105,8 @@ public class InventoryController : Controller
                 requiresClearCoat = p.RequiresClearCoat,
                 coverageSqFtPerLb = p.CoverageSqFtPerLb,
                 transferEfficiency = p.TransferEfficiency
-            });
+            })
+            .ToList();
 
         return Json(results);
     }