add healthcheck

Dockerfile

@@ -28,3 +28,6 @@ COPY --from=builder /app/target/x86_64-unknown-linux-musl/release/world-id-teleg
 USER 100
 EXPOSE 8000
 CMD ["/app/world-id-telegram"]
+
+HEALTHCHECK --interval=5m --timeout=3s \
+  CMD curl -f http://localhost:8000/health || exit 1

src/server/mod.rs

@@ -27,6 +27,7 @@ pub async fn start(bot: Bot, config: AppConfig, bot_data: User, join_requests: J
 				Redirect::permanent(&format!("https://t.me/{}", bot_data.username.unwrap()))
 			}),
 		)
+		.route("/health", get(|| async { "OK" }))
 		.route(
 			"/verify/:chat_id/:user_id",
 			get(verify_page).post(verify_api),