UI: task sessions in agent detail, ApprovalCard extraction, and company settings page

Show task sessions list in AgentDetail with per-session reset. Extract
ApprovalCard into standalone component from Approvals and Inbox pages,
reducing duplication. Add CompanySettings page with issuePrefix configuration.
Fix Sidebar active state for settings route. Display sessionDisplayId
in agent properties. Various cleanups to Approvals and Inbox pages.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/App.tsx

@@ -16,6 +16,7 @@ import { Costs } from "./pages/Costs";
 import { Activity } from "./pages/Activity";
 import { Inbox } from "./pages/Inbox";
 import { MyIssues } from "./pages/MyIssues";
+import { CompanySettings } from "./pages/CompanySettings";
 import { DesignGuide } from "./pages/DesignGuide";
 
 export function App() {
@@ -25,6 +26,7 @@ export function App() {
         <Route index element={<Navigate to="/dashboard" replace />} />
         <Route path="dashboard" element={<Dashboard />} />
         <Route path="companies" element={<Companies />} />
+        <Route path="company/settings" element={<CompanySettings />} />
         <Route path="org" element={<Navigate to="/agents" replace />} />
         <Route path="agents" element={<Agents />} />
         <Route path="agents/:agentId" element={<AgentDetail />} />