feat: Agent Health page with progressive filtering and GroupCard component

Add URL-driven Agent Health page (/agents, /agents/:appId,
/agents/:appId/:instanceId) that progressively narrows from all
applications to a single instance with trend charts. Create
generic GroupCard composite for grouping instances by application.
Expand mock data to 8 instances across 4 apps with varied states.
Split sidebar Agents header into navigable link + collapse chevron.
Update agent tree paths to /agents/:appId/:instanceId. Add EventFeed
with lifecycle events. Change SidebarAgent.tps from string to number.

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

src/App.tsx

@@ -6,7 +6,6 @@ import { ExchangeDetail } from './pages/ExchangeDetail/ExchangeDetail'
 import { AgentHealth } from './pages/AgentHealth/AgentHealth'
 import { Inventory } from './pages/Inventory/Inventory'
 import { AppDetail } from './pages/AppDetail/AppDetail'
-import { AgentDetail } from './pages/AgentDetail/AgentDetail'
 import { Admin } from './pages/Admin/Admin'
 import { ApiDocs } from './pages/ApiDocs/ApiDocs'
 
@@ -17,8 +16,7 @@ export default function App() {
       <Route path="/metrics" element={<Metrics />} />
       <Route path="/routes/:id" element={<RouteDetail />} />
       <Route path="/exchanges/:id" element={<ExchangeDetail />} />
-      <Route path="/agents" element={<AgentHealth />} />
-      <Route path="/agents/:id" element={<AgentDetail />} />
+      <Route path="/agents/*" element={<AgentHealth />} />
       <Route path="/apps/:id" element={<AppDetail />} />
       <Route path="/admin" element={<Admin />} />
       <Route path="/api-docs" element={<ApiDocs />} />