fix(eval): decode JSON-encoded external_recipients in alert_skill check

The create_metric_alert tool returns external_recipients as a JSON-encoded
string (e.g. '["email@example.com"]') rather than a list. Use json.loads
before falling back to CSV splitting so recipients comparison works correctly.

JIRA: GDAI-1830
risk: nonprod

Author: zdenekmusil-gd

packages/gooddata-eval/src/gooddata_eval/core/agentic/alert_skill.py

@@ -99,7 +99,12 @@ def _check_recipients(expected: CatalogMetricAlert, actual_args: dict) -> bool:
         return True
     act_recip_raw = actual_args.get("recipients", actual_args.get("external_recipients"))
     if isinstance(act_recip_raw, str):
-        act_recip = _parse_recipients(act_recip_raw)
+        # external_recipients is JSON-encoded (e.g. '["email@example.com"]')
+        try:
+            parsed = json.loads(act_recip_raw)
+            act_recip = parsed if isinstance(parsed, list) else _parse_recipients(act_recip_raw)
+        except (json.JSONDecodeError, ValueError):
+            act_recip = _parse_recipients(act_recip_raw)
     elif isinstance(act_recip_raw, list):
         act_recip = act_recip_raw
     else: