Add an artist listing page and improve SEO for various pages

Introduces a new `/kuenstler` page, API endpoint `/api/artists`, and enhances meta tags on `index.html` and for crawler requests on `/kuenstler`. Adds `KuenstlerPage.tsx` and updates `routes.ts` and `index.html`.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 401e2ec0-e00d-4f10-9d0e-60f3d479f9a5
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Event-Id: 69ee4fdb-c617-4cdd-b9f6-d3fab268d533
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/60d372ff-2c10-46c7-b01b-10c3435136b0/401e2ec0-e00d-4f10-9d0e-60f3d479f9a5/qFrskyV

client/src/App.tsx

@@ -11,6 +11,7 @@ import GeschichteLiedPage from "@/pages/GeschichteLiedPage";
 import GipfelstammtischPage from "@/pages/GipfelstammtischPage";
 import LivePage from "@/pages/LivePage";
 import PlayerPage from "@/pages/PlayerPage";
+import KuenstlerPage from "@/pages/KuenstlerPage";
 import AdminPage from "@/pages/admin";
 import PrivacyPolicy from "@/pages/PrivacyPolicy";
 import TermsOfService from "@/pages/TermsOfService";
@@ -27,6 +28,7 @@ function Router() {
       <Route path="/gipfelstammtisch" component={GipfelstammtischPage} />
       <Route path="/live" component={LivePage} />
       <Route path="/player" component={PlayerPage} />
+      <Route path="/kuenstler" component={KuenstlerPage} />
       <Route path="/admin" component={AdminPage} />
       <Route path="/privacy" component={PrivacyPolicy} />
       <Route path="/terms" component={TermsOfService} />