Fix powder catalog lookup: exact match auto-fills, partials show picker modal

- CatalogLookup now returns all partial color name matches ranked by
  specificity (exact vendor+color first, same-vendor partial, cross-vendor)
  with isExact flag so JS can decide to auto-fill vs show modal
- Removed cross-vendor fallback that was silently overwriting manufacturer
  field with wrong brand when vendor-scoped search found nothing
- Picker modal now includes "Not listed — search online" option that
  triggers AI lookup as an escape hatch from the catalog results

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

src/PowderCoating.Web/wwwroot/js/inventory-catalog-lookup.js

@@ -62,23 +62,25 @@
             const items = await resp.json();
 
             if (items.length === 0) {
-                // No catalog match — fall back to AI if available
-                hideStatus();
-                if (typeof window._runInventoryAiLookup === 'function') {
-                    showStatus('info', '<span class="spinner-border spinner-border-sm me-1"></span>Not in catalog — searching with AI…');
-                    await window._runInventoryAiLookup();
-                } else {
-                    showStatus('warning', 'No match found in the catalog. Enter details manually or enable AI Lookup.');
-                }
+                // Nothing in catalog — go straight to AI
+                await runAiOrWarn();
                 return;
             }
 
-            if (items.length === 1) {
+            // Single exact match (vendor + color name both match precisely) — auto-fill
+            if (items.length === 1 && items[0].isExact) {
                 await fillFields(items[0]);
                 return;
             }
 
-            // Multiple matches — let the user pick via modal
+            // Exact match exists but so do other results — auto-fill the exact one
+            const exactMatches = items.filter(i => i.isExact);
+            if (exactMatches.length === 1) {
+                await fillFields(exactMatches[0]);
+                return;
+            }
+
+            // No exact match (or ambiguous) — show picker modal with "Not Listed" escape hatch
             hideStatus();
             showPickerModal(items);
 
@@ -89,6 +91,18 @@
         }
     });
 
+    // ── AI fallback helper ───────────────────────────────────────────────────
+
+    async function runAiOrWarn() {
+        hideStatus();
+        if (typeof window._runInventoryAiLookup === 'function') {
+            showStatus('info', '<span class="spinner-border spinner-border-sm me-1"></span>Not in catalog — searching online with AI…');
+            await window._runInventoryAiLookup();
+        } else {
+            showStatus('warning', 'No match found in the catalog. Enter details manually or enable AI Lookup.');
+        }
+    }
+
     // ── Fill fields from a catalog result ────────────────────────────────────
 
     async function fillFields(item) {
@@ -368,6 +382,12 @@
               <div class="modal-body p-0">
                 <div class="list-group list-group-flush">${rows}</div>
               </div>
+              <div class="modal-footer py-2 justify-content-start">
+                <button type="button" class="btn btn-sm btn-outline-secondary" id="catalogPickerNotListed">
+                  <i class="bi bi-search me-1"></i>Not listed — search online
+                </button>
+                <span class="text-muted small ms-2">Uses AI to look up the exact product</span>
+              </div>
             </div>
           </div>
         </div>`;
@@ -383,6 +403,11 @@
             });
         });
 
+        document.getElementById('catalogPickerNotListed').addEventListener('click', function () {
+            bsModal.hide();
+            runAiOrWarn();
+        });
+
         bsModal.show();
     }