Improve UX with merged run view, method badges, grouped encounters, and mobile nav

Merges the run dashboard into the encounters page as a unified view at /runs/:runId,
adds encounter method grouping in the modal and badges on route rows, improves the
home page with recent runs, adds mobile hamburger nav, and polishes empty states.

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

frontend/src/App.tsx

@@ -1,7 +1,7 @@
 import { Routes, Route, Navigate } from 'react-router-dom'
 import { Layout } from './components'
 import { AdminLayout } from './components/admin'
-import { Home, NewRun, RunList, RunDashboard, RunEncounters } from './pages'
+import { Home, NewRun, RunList, RunEncounters } from './pages'
 import {
   AdminGames,
   AdminGameDetail,
@@ -17,8 +17,8 @@ function App() {
         <Route index element={<Home />} />
         <Route path="runs" element={<RunList />} />
         <Route path="runs/new" element={<NewRun />} />
-        <Route path="runs/:runId" element={<RunDashboard />} />
-        <Route path="runs/:runId/encounters" element={<RunEncounters />} />
+        <Route path="runs/:runId" element={<RunEncounters />} />
+        <Route path="runs/:runId/encounters" element={<Navigate to=".." relative="path" replace />} />
         <Route path="admin" element={<AdminLayout />}>
           <Route index element={<Navigate to="/admin/games" replace />} />
           <Route path="games" element={<AdminGames />} />