feat: add application log panel to agent health page

Add the same log + timeline side-by-side layout from AgentInstance to
the AgentHealth page (/agents/{appId}). Includes search input, level
filter pills, sort toggle, and refresh button — matching the instance
page design exactly.

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

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

@@ -204,9 +204,106 @@
   color: var(--text-muted);
 }
 
+/* Log + Timeline side by side */
+.bottomRow {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 14px;
+  margin-top: 20px;
+}
+
+/* Log viewer */
+.logCard {
+  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;
+}
+
+.logHeader {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 12px 16px;
+  border-bottom: 1px solid var(--border-subtle);
+}
+
+.logToolbar {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 8px 12px;
+  border-bottom: 1px solid var(--border-subtle);
+  background: var(--bg-surface);
+}
+
+.logSearchWrap {
+  position: relative;
+  flex: 1;
+  min-width: 0;
+}
+
+.logSearchInput {
+  width: 100%;
+  padding: 5px 28px 5px 10px;
+  border: 1px solid var(--border-subtle);
+  border-radius: var(--radius-sm);
+  background: var(--bg-body);
+  color: var(--text-primary);
+  font-size: 12px;
+  font-family: var(--font-body);
+  outline: none;
+}
+
+.logSearchInput:focus {
+  border-color: var(--amber);
+}
+
+.logSearchInput::placeholder {
+  color: var(--text-faint);
+}
+
+.logSearchClear {
+  position: absolute;
+  right: 4px;
+  top: 50%;
+  transform: translateY(-50%);
+  background: none;
+  border: none;
+  color: var(--text-muted);
+  cursor: pointer;
+  font-size: 14px;
+  padding: 0 4px;
+  line-height: 1;
+}
+
+.logClearFilters {
+  background: none;
+  border: none;
+  color: var(--text-muted);
+  font-size: 11px;
+  cursor: pointer;
+  padding: 2px 6px;
+  white-space: nowrap;
+}
+
+.logClearFilters:hover {
+  color: var(--text-primary);
+}
+
+.logEmpty {
+  padding: 24px;
+  text-align: center;
+  color: var(--text-faint);
+  font-size: 12px;
+}
+
 /* Event card (timeline panel) */
 .eventCard {
-  margin-top: 20px;
   background: var(--bg-surface);
   border: 1px solid var(--border-subtle);
   border-radius: var(--radius-lg);