Fix IBKR managed symbols in reports

[Pigbibi]

Summary

• prefer configured strategy managed_symbols when building runtime reports
• avoid falling back to only the safe-haven symbol when ranking_pool is empty
• add regression coverage for SOXL/SOXX runtime reports

Tests

• git diff --check
• .venv/bin/python -m pytest tests/test_request_handling.py::test_execution_report_prefers_configured_managed_symbols_without_ranking_pool tests/test_request_handling.py::test_handle_request_persists_machine_readable_report -q
• .venv/bin/python -m pytest -q