Add a new page for Gipfelstammtisch videos

Introduce a new route and page component for "Gipfelstammtisch" content, and add navigation links to access it from various parts of the application.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 890577b1-c154-40a4-a177-a0c6d55320c3
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/8cc42625-c1f5-4e43-99bd-77f2c4dedee2/890577b1-c154-40a4-a177-a0c6d55320c3/2xHHKQn

client/src/App.tsx

@@ -7,6 +7,7 @@ import Home from "@/pages/home";
 import VideoPage from "@/pages/VideoPage";
 import FolxStadlPage from "@/pages/FolxStadlPage";
 import GeschichteLiedPage from "@/pages/GeschichteLiedPage";
+import GipfelstammtischPage from "@/pages/GipfelstammtischPage";
 import NotFound from "@/pages/not-found";
 
 function Router() {
@@ -16,6 +17,7 @@ function Router() {
       <Route path="/video/:id" component={VideoPage} />
       <Route path="/folx-stadl" component={FolxStadlPage} />
       <Route path="/geschichte-lied" component={GeschichteLiedPage} />
+      <Route path="/gipfelstammtisch" component={GipfelstammtischPage} />
       <Route component={NotFound} />
     </Switch>
   );