Fix audit finding F13: Tighten subactor authority token matching and fix diagnostic summary key.
Recorded from user prompt in conversation 78d87a8b-d52c-4b44-b8f5-077656700b95.
src/data2dsl_subactor.pyvalidate_delegation_envelope with exact token matching against VALID_AUTHORITY_KEYWORDS.simulate_self_healing_cycle to lookup diag_profile.get("summary") so that diagnostic_severity_summary receives the severity counts object.tests/test_subactor_f13.pypytest tests/test_subactor_f13.py: 2/2 passed.