feat: enhance EventFeed timeline and Agent Health page styling

- EventFeed: 28px icon circles with severity colors, stacked message/timestamp,
  search input with clear button, ReactNode message support with searchText field
- Agent Health: timeline wrapped in card panel, instance listing as proper table,
  colored Badge pills for live counts, removed shift pill
- Input primitive: onClear prop with × button for all search fields
- Sidebar: Agents section collapsible like Applications, collapse state persisted
  to localStorage
- FilterBar/Sidebar: clear buttons on all search inputs

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

src/pages/AgentHealth/AgentHealth.module.css

@@ -49,7 +49,7 @@
 .sectionHeaderRow {
   display: flex;
   align-items: center;
-  justify-content: space-between;
+  gap: 8px;
   margin-bottom: 12px;
 }
 
@@ -122,46 +122,65 @@
   flex-shrink: 0;
 }
 
-/* Instance header row */
-.instanceHeader {
-  display: grid;
-  grid-template-columns: 8px minmax(80px, 1.2fr) auto auto auto auto auto;
-  gap: 12px;
-  padding: 4px 16px;
+/* Instance table */
+.instanceTable {
+  width: 100%;
+  border-collapse: collapse;
+  font-size: 12px;
+}
+
+.instanceTable thead th {
+  padding: 4px 12px;
   font-size: 9px;
   font-weight: 600;
   text-transform: uppercase;
   letter-spacing: 0.5px;
   color: var(--text-faint);
+  text-align: left;
   border-bottom: 1px solid var(--border-subtle);
+  white-space: nowrap;
+}
+
+.thStatus {
+  width: 12px;
+}
+
+.tdStatus {
+  width: 12px;
+  text-align: center;
 }
 
 /* Instance row */
 .instanceRow {
-  display: grid;
-  grid-template-columns: 8px minmax(80px, 1.2fr) auto auto auto auto auto;
-  gap: 12px;
-  align-items: center;
-  padding: 8px 16px;
-  border-bottom: 1px solid var(--border-subtle);
-  font-size: 12px;
-  text-decoration: none;
-  color: inherit;
-  transition: background 0.1s;
   cursor: pointer;
+  transition: background 0.1s;
 }
 
-.instanceRow:last-child {
+.instanceRow td {
+  padding: 8px 12px;
+  border-bottom: 1px solid var(--border-subtle);
+  white-space: nowrap;
+}
+
+.instanceRow:last-child td {
   border-bottom: none;
 }
 
-.instanceRow:hover {
+.instanceRow:hover td {
   background: var(--bg-hover);
 }
 
-.instanceRowActive {
+.instanceRowActive td {
   background: var(--amber-bg);
-  border-left: 3px solid var(--amber);
+}
+
+.instanceRowActive td:first-child {
+  box-shadow: inset 3px 0 0 var(--amber);
+}
+
+/* Chart expansion row */
+.chartRow td {
+  padding: 0;
 }
 
 /* Instance fields */
@@ -217,7 +236,23 @@
   letter-spacing: 0.5px;
 }
 
-/* Event section */
-.eventSection {
+/* Event card (timeline panel) */
+.eventCard {
   margin-top: 20px;
+  background: var(--bg-surface);
+  border: 1px solid var(--border-subtle);
+  border-radius: var(--radius-lg);
+  box-shadow: var(--shadow-card);
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+  max-height: 420px;
+}
+
+.eventCardHeader {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 10px 16px;
+  border-bottom: 1px solid var(--border-subtle);
 }