add a basic landing page

projects/backend/src/service/app.service.ts

@@ -0,0 +1,15 @@
+import { PlayerModel } from "../model/player";
+import { AppStatistics } from "@ssr/common/types/backend/app-statistics";
+
+export class AppService {
+  /**
+   * Gets the app statistics.
+   */
+  public static async getAppStatistics(): Promise<AppStatistics> {
+    const trackedPlayers = await PlayerModel.countDocuments();
+
+    return {
+      trackedPlayers,
+    };
+  }
+}