Öffentliche Roadmap-Seite aus Gitea-Milestones

- GET /api/roadmap (public): Milestones des Setting roadmap_repo, 5-min-Cache,
  letzter guter Stand als Fallback bei Gitea-Ausfall
- /roadmap: Gruppen In Arbeit / Geplant / Fertig, Fortschrittsbalken im Brand-Look,
  Ziel-Monat, Markdown-Beschreibungen; Nav-Link öffentlich
- Setup-Seite: Roadmap-Repo konfigurierbar

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/App.jsx

@@ -3,6 +3,7 @@ import { Routes, Route, NavLink, Navigate } from 'react-router-dom';
 import { apiGet } from './api.js';
 import Devlogs from './pages/Devlogs.jsx';
 import Changelog from './pages/Changelog.jsx';
+import Roadmap from './pages/Roadmap.jsx';
 import Commits from './pages/Commits.jsx';
 import Settings from './pages/Settings.jsx';
 
@@ -70,6 +71,7 @@ export default function App() {
 
                 <nav className="nav-links">
                     <NavLink to="/devlogs">Devlog</NavLink>
+                    <NavLink to="/roadmap">Roadmap</NavLink>
                     <NavLink to="/changelog">Changelog</NavLink>
                     {me.admin && <NavLink to="/commits">Commits</NavLink>}
                     {me.admin && <NavLink to="/settings">Setup</NavLink>}
@@ -94,6 +96,7 @@ export default function App() {
                 <Routes>
                     <Route path="/" element={<Navigate to="/devlogs" replace />} />
                     <Route path="/devlogs" element={<Devlogs me={me} />} />
+                    <Route path="/roadmap" element={<Roadmap />} />
                     <Route path="/changelog" element={<Changelog />} />
                     <Route path="/commits" element={<Commits me={me} />} />
                     <Route path="/settings" element={<Settings me={me} />} />