refactor(openclaw): extract gateway url validator

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/openclaw/dispatcher.ts

@@ -1,5 +1,5 @@
 import { spawn } from "bun"
-import { validateGatewayUrl } from "./config"
+import { validateGatewayUrl } from "./gateway-url-validation"
 import type { OpenClawGateway, WakeResult } from "./types"
 
 const DEFAULT_HTTP_TIMEOUT_MS = 10_000