feat(automations): add event trigger source, selector and registration

surfsense_backend/tests/unit/automations/triggers/builtin/event/test_definition.py

@@ -0,0 +1,18 @@
+"""The ``event`` trigger self-registers on the triggers store at import."""
+
+from __future__ import annotations
+
+import pytest
+
+from app.automations.triggers import get_trigger
+from app.automations.triggers.builtin.event.params import EventTriggerParams
+
+pytestmark = pytest.mark.unit
+
+
+def test_event_trigger_is_registered() -> None:
+    definition = get_trigger("event")
+
+    assert definition is not None
+    assert definition.type == "event"
+    assert definition.params_model is EventTriggerParams