feat(n8n-webhook): expand action bus starter workflow

skills/n8n-webhook/assets/test-fetch-and-normalize-url.json

@@ -0,0 +1,8 @@
+{
+  "action": "fetch_and_normalize_url",
+  "request_id": "test-fetch-001",
+  "args": {
+    "url": "https://example.com",
+    "max_chars": 2000
+  }
+}