Add scheduler fairness summary to sustained feeds

[hyeokjun32]

Summary

• add an additive scheduler fairness summary to sustained operation timelines and EdgeEnv telemetry feeds
• expose protected high-priority tasks, scheduler-delay/starvation risk, degraded workers, and per-task fairness context without changing Lab/EdgeEnv ownership
• update the EdgeEnv feed checker, curated scheduler-delay sample, sample README entries, and orchestration summary contract docs

Tests

• PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m pytest -q -p no:cacheprovider tests/test_multi_workload_sustained.py tests/test_sample_telemetry_artifacts.py tests/test_docs_links.py tests/test_scripts.py
• PYTHONDONTWRITEBYTECODE=1 .venv/bin/python -m pytest -q -p no:cacheprovider
• git diff --check
• env 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/inferedge_orchestrator_fairness_smoke/report.json --frames 8 --edgeenv-feed-output /tmp/inferedge_orchestrator_fairness_smoke/edgeenv_runtime_telemetry_feed.json
• env PYTHONPATH=src PYTHONDONTWRITEBYTECODE=1 .venv/bin/python scripts/check_edgeenv_runtime_feed_contract.py --feed /tmp/inferedge_orchestrator_fairness_smoke/edgeenv_runtime_telemetry_feed.json --require-device-local-producer