fix(lint): Black formatting + C901 exemption for legal_routes

Black-format 6 files (l4, l7 detectors + tests, legal_routes + route tests).
Add C901 to legal_routes.py per-file-ignores — register_legal_routes nests
4 route handlers (complexity 15) following the same pattern as other complex
route files in the project.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: MARS

pyproject.toml

@@ -224,5 +224,5 @@ select = ["E", "F", "W", "I", "N", "UP", "C90", "B"]
 "tests/odia_legal/test_l4_ministerial_duty.py" = ["E501"]
 "src/odia_legal/detectors/l7_regulatory_authority.py" = ["E501"]
 "tests/odia_legal/test_l7_regulatory_authority.py" = ["E501"]
-"src/oraculus_di_auditor/interface/routes/legal_routes.py" = ["E501"]
+"src/oraculus_di_auditor/interface/routes/legal_routes.py" = ["E501", "C901"]
 "tests/legal/test_legal_routes.py" = ["E501"]