style(extensions): use yaml.safe_dump when writing catalog config

The catalog add/remove handlers wrote the integration catalog config with
yaml.dump. Switch to yaml.safe_dump to align with the SafeDumper used by the
presets commands and to refuse emitting !!python/object tags if a non-basic
value ever reaches the config dict.

Output is unchanged for the current basic-type payload (str/int/bool/dict/
list) — this is a defensive/consistency change, not a behavioral fix.

Author: darion-yaphet

tests/test_extension_update_hardening.py

@@ -111,7 +111,7 @@ def mock_download_fail(*args, **kwargs):
 
 def test_extension_update_skills_backup_no_collision(project_dir, monkeypatch):
     """Regression: skills agents name every command file SKILL.md (one per
-    per-command subdir). Backup must keep the per-command path so rollback
+    command subdirectory). Backup must keep the per-command path so rollback
     restores each skill's own content instead of overwriting them onto a
     single backup path."""
     monkeypatch.chdir(project_dir)