feat(web,coder): add analytics + results pages for token usage and run history

New /analytics route: token usage dashboard with aggregate summary,
per-session breakdown, context window stats, and per-category token
distribution. Data served from existing agent_sessions + tool_cost_stats.

New /results route: browsable archive of orchestrator flow runs and
arena battles. Two-tab layout (Analysis Runs / Arena Battles) using
existing API endpoints (no new backend).

Sidebar gains Results (ScrollText icon) and Token Analytics (BarChart3
icon) nav buttons above Settings.

apps/web/src/App.tsx

@@ -7,6 +7,8 @@ import { Home } from '@/pages/Home';
 import { Project } from '@/pages/Project';
 import { Session } from '@/pages/Session';
 import { Settings } from '@/pages/Settings';
+import { Analytics } from '@/pages/Analytics';
+import { Results } from '@/pages/Results';
 import { Toaster } from '@/components/ui/sonner';
 import { useUserEvents } from '@/hooks/useUserEvents';
 import { useCoderUserEvents } from '@/hooks/useCoderUserEvents';
@@ -95,6 +97,8 @@ function AppShell() {
             <Route path="/project/:id" element={<Project />} />
             <Route path="/session/:id" element={<Session />} />
             <Route path="/settings" element={<Settings />} />
+            <Route path="/analytics" element={<Analytics />} />
+            <Route path="/results" element={<Results />} />
           </Routes>
         </main>
         <MobileRightRailBackdrop />