fix: use hammer.donovankelly.xyz for all gateway access (HQ-21)

- Single domain for hooks + WebSocket (path-based routing)
- No need for ws.hammer or hooks.hammer subdomains
- Caddy proxies everything to gateway on this VPS

frontend/src/pages/ChatPage.tsx

@@ -1,8 +1,8 @@
 import { useState, useEffect, useRef, useCallback } from "react";
 import { GatewayClient } from "../lib/gateway";
 
-const WS_URL = import.meta.env.VITE_WS_URL || `wss://${window.location.hostname.replace("dash.", "ws.hammer.")}`;
-const WS_TOKEN = import.meta.env.VITE_WS_TOKEN || "";
+const WS_URL = import.meta.env.VITE_WS_URL || "wss://hammer.donovankelly.xyz";
+const WS_TOKEN = import.meta.env.VITE_WS_TOKEN || import.meta.env.VITE_GATEWAY_TOKEN || "";
 
 interface ChatMessage {
   role: "user" | "assistant" | "system";