refactor: restructure RBAC page to container + tab components, add CSS module

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

ui/src/pages/AgentHealth/AgentHealth.module.css

@@ -82,3 +82,99 @@
   font-weight: 600;
   color: var(--text-primary);
 }
+
+/* DetailPanel: Overview tab */
+
+.overviewContent {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+  padding: 4px 0;
+}
+
+.overviewRow {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.detailList {
+  display: flex;
+  flex-direction: column;
+  gap: 0;
+  margin: 0;
+  padding: 0;
+}
+
+.detailRow {
+  display: flex;
+  justify-content: space-between;
+  align-items: baseline;
+  padding: 6px 0;
+  border-bottom: 1px solid var(--border-subtle);
+  font-size: 12px;
+}
+
+.detailRow:last-child {
+  border-bottom: none;
+}
+
+.detailRow dt {
+  color: var(--text-muted);
+  font-weight: 500;
+}
+
+.detailRow dd {
+  margin: 0;
+  color: var(--text-primary);
+  text-align: right;
+}
+
+.metricsSection {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.metricLabel {
+  font-size: 11px;
+  font-weight: 600;
+  color: var(--text-muted);
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+}
+
+/* DetailPanel: Performance tab */
+
+.performanceContent {
+  display: flex;
+  flex-direction: column;
+  gap: 20px;
+  padding: 4px 0;
+}
+
+.chartSection {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.chartLabel {
+  font-size: 11px;
+  font-weight: 600;
+  color: var(--text-muted);
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+}
+
+.emptyChart {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  height: 80px;
+  background: var(--bg-surface-raised);
+  border: 1px dashed var(--border-subtle);
+  border-radius: var(--radius-md);
+  font-size: 12px;
+  color: var(--text-muted);
+}