WebSocket real-time updates: faster polling + network events

- Reduce polling interval to 5 seconds for faster updates
- Add network update events (peer count changes)
- Include block type (PoS/PoW) in newBlock events
- Track connected WebSocket clients
- Emit networkUpdate when peer count changes

This enables real-time live feed on the explorer frontend.

node_modules/engine.io/build/transports-uws/websocket.d.ts

@@ -0,0 +1,32 @@
+import { Transport } from "../transport";
+export declare class WebSocket extends Transport {
+    protected perMessageDeflate: any;
+    private socket;
+    /**
+     * WebSocket transport
+     *
+     * @param req
+     */
+    constructor(req: any);
+    /**
+     * Transport name
+     */
+    get name(): string;
+    /**
+     * Advertise upgrade support.
+     */
+    get handlesUpgrades(): boolean;
+    /**
+     * Writes a packet payload.
+     *
+     * @param {Array} packets
+     * @private
+     */
+    send(packets: any): void;
+    /**
+     * Closes the transport.
+     *
+     * @private
+     */
+    doClose(fn: any): void;
+}