fix: add groupName to ExecutionSummary, locale format stat values, inspect column, fix duplicate keys

- Added groupName field to ExecutionSummary Java record and OpenSearch mapper
- Dashboard stat cards use locale-formatted numbers (en-US)
- Added inspect column (↗) linking directly to exchange detail page
- Fixed duplicate React key warning from two columns sharing executionId key

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

ui/src/pages/Dashboard/Dashboard.module.css

@@ -83,6 +83,24 @@
   padding-top: 2px;
 }
 
+.inspectLink {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 24px;
+  height: 24px;
+  font-size: 14px;
+  color: var(--text-muted);
+  text-decoration: none;
+  border-radius: 4px;
+  transition: color 0.15s, background 0.15s;
+}
+
+.inspectLink:hover {
+  color: var(--accent, #c6820e);
+  background: var(--bg-hover);
+}
+
 .openDetailLink {
   display: inline-block;
   font-size: 13px;