Fix gateway proxy: /gateway is 8 chars not 7, was creating 18789y port

app.py

@@ -463,7 +463,7 @@ async def proxy_openclaw_gateway(request: Request, path: str = ""):
         raise HTTPException(status_code=503, detail="httpx not installed; cannot proxy to Clawdbot gateway")
     target_path = request.url.path
     if target_path.startswith("/gateway"):
-        target_path = target_path[7:] or "/"  # strip /gateway -> / or /foo
+        target_path = target_path[8:] or "/"  # strip /gateway -> / or /foo
     target = f"{OPENCLAW_GATEWAY_URL}{target_path}"
     if request.url.query:
         target += "?" + request.url.query