feat: label source branch deletion security events

tests/test_security_center.py

@@ -6,6 +6,12 @@ from pathlib import Path
 SECURITY_CENTER = Path(__file__).parents[1] / "frontend" / "security-center.js"
 
 
+def test_source_branch_cleanup_has_a_specific_security_activity_label():
+    source = SECURITY_CENTER.read_text()
+
+    assert "source_branch_deleted: 'Source branch deleted'" in source
+
+
 def test_open_security_center_loads_all_sections_concurrently_and_is_awaitable():
     harness = f"""
 const attachSecurityCenter=require({json.dumps(str(SECURITY_CENTER))});