refactor: Hub二进制改为Docker构建时下载，优化部署流程与worker初始化

- Dockerfile: 移除COPY预编译二进制，改为构建时通过HUB_TAG从GitHub Release下载
- CI: 移除artifact上传/下载步骤，通过build-args传递Hub tag
- deploy.sh: 重构参数解析，支持--hub-tag指定版本，跟踪tag变化触发重建
- build.sh: 新增--image模式支持构建并推送Hub Docker镜像
- hub.rs: worker连接时同步所有节点在线状态，避免状态不一致
- proxy_nodes: 启动时主动建立Hub worker连接，消除懒连接窗口期
- docker-compose.yml: app镜像支持APP_IMAGE环境变量配置
- README: 更新部署文档，推荐本地构建方式

aether-hub/src/hub.rs

@@ -258,7 +258,8 @@ impl HubRouter {
 
     pub fn register_worker(&self, conn: Arc<WorkerConn>) {
         info!(worker_id = conn.id, "worker connected");
-        self.worker_conns.insert(conn.id, conn);
+        self.worker_conns.insert(conn.id, conn.clone());
+        self.sync_node_status_to_worker(&conn);
     }
 
     pub fn unregister_worker(&self, conn_id: u64) {
@@ -667,6 +668,28 @@ impl HubRouter {
         );
     }
 
+    /// When a worker connects, sync all current node statuses so worker state
+    /// is consistent even if proxies connected before this worker came online.
+    fn sync_node_status_to_worker(&self, worker: &Arc<WorkerConn>) {
+        let snapshot: Vec<(String, usize)> = {
+            let map = self.proxy_conns.read();
+            map.iter()
+                .map(|(node_id, conns)| (node_id.clone(), conns.len()))
+                .collect()
+        };
+
+        for (node_id, conn_count) in &snapshot {
+            let frame = protocol::encode_node_status(node_id, *conn_count > 0, *conn_count);
+            let _ = worker.send(Message::Binary(frame.into()));
+        }
+
+        debug!(
+            worker_id = worker.id,
+            nodes_synced = snapshot.len(),
+            "synced NODE_STATUS snapshot to worker"
+        );
+    }
+
     // -----------------------------------------------------------------------
     // Stats
     // -----------------------------------------------------------------------