Add sustained scenario coverage summary

[hyeokjun32]

Summary

• add an additive scenario_coverage block to operation_timeline_summary so sustained runs expose cycles, sample counts, producer sources, and Lab ownership boundaries
• print scenario-coverage in the sustained CLI and EdgeEnv feed contract checker first-read output
• validate scenario_coverage boundary/type markers and cover the new output in tests

Tests

• PYTHONPATH=src PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m pytest tests/test_multi_workload_sustained.py tests/test_scripts.py -q -p no:cacheprovider
• PYTHONPATH=src PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m inferedge_orchestrator run-multi-workload-sustained --config configs/agent_multi_workload_sustained_device_local.json --output /tmp/orchestrator-scenario-coverage.json --edgeenv-feed-output /tmp/orchestrator-scenario-coverage-feed.json --frames 4
• PYTHONPATH=src PYTHONDONTWRITEBYTECODE=1 .venv/bin/python scripts/check_edgeenv_runtime_feed_contract.py --feed /tmp/orchestrator-scenario-coverage-feed.json --require-device-local-producer
• PYTHONPATH=src PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m pytest -q -p no:cacheprovider
• PYTHONPATH=src PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m compileall -q src scripts
• git diff --check