feat: include tap attributes in cmd-K full-text search

Add attributes_text flattened field to OpenSearch indexing for both
execution and processor levels. Include in full-text search queries,
wildcard matching, and highlighting. Merge processor-level attributes
into ExecutionSummary. Add 'attribute' category to CommandPalette
(design-system 0.1.17) with per-key-value results in the search UI.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/LayoutShell.tsx

@@ -140,8 +140,30 @@ function LayoutContent() {
       serverFiltered: true,
       matchContext: e.highlight ?? undefined,
     }));
-    return [...catalogData, ...exchangeItems];
-  }, [catalogData, exchangeResults]);
+
+    const attributeItems: SearchResult[] = [];
+    if (debouncedQuery) {
+      const q = debouncedQuery.toLowerCase();
+      for (const e of exchangeResults?.data || []) {
+        if (!e.attributes) continue;
+        for (const [key, value] of Object.entries(e.attributes as Record<string, string>)) {
+          if (key.toLowerCase().includes(q) || String(value).toLowerCase().includes(q)) {
+            attributeItems.push({
+              id: `${e.executionId}-attr-${key}`,
+              category: 'attribute' as const,
+              title: `${key} = "${value}"`,
+              badges: [{ label: e.status, color: statusToColor(e.status) }],
+              meta: `${e.executionId} · ${e.routeId} · ${e.applicationName ?? ''}`,
+              path: `/exchanges/${e.executionId}`,
+              serverFiltered: true,
+            });
+          }
+        }
+      }
+    }
+
+    return [...catalogData, ...exchangeItems, ...attributeItems];
+  }, [catalogData, exchangeResults, debouncedQuery]);
 
   const breadcrumb = useMemo(() => {
     const LABELS: Record<string, string> = {