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/gateway-url-validation.ts

@@ -0,0 +1,18 @@
+export function validateGatewayUrl(url: string): boolean {
+  try {
+    const parsed = new URL(url)
+    if (parsed.protocol === "https:") return true
+    if (
+      parsed.protocol === "http:" &&
+      (parsed.hostname === "localhost" ||
+        parsed.hostname === "127.0.0.1" ||
+        parsed.hostname === "::1" ||
+        parsed.hostname === "[::1]")
+    ) {
+      return true
+    }
+    return false
+  } catch {
+    return false
+  }
+}