fix(api): resolve event loop starvation in health/metrics endpoints

[sushantguri]

Fixes # — replaces blocking psutil.cpu_percent(interval=1) with non-blocking interval=None wrapped in asyncio.to_thread(). Metrics latency: ~1,000ms → 0.8ms. Regression test added

[Copilot]

Pull request overview

This PR targets event-loop starvation in the archived v1 FastAPI health/metrics paths by removing the 1s-blocking psutil.cpu_percent(interval=1) usage and offloading OS-metrics collection to background threads to keep the async loop responsive.

Changes:

• Offload health/metrics router metrics collection (get_system_metrics, get_detailed_metrics) via asyncio.to_thread, and switch cpu_percent to interval=None.
• Update the v1 MetricsService system metrics collection to gather psutil metrics in a background thread and avoid interval=1.
• Add a concurrency regression test and document the fix in CHANGELOG.md.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
CHANGELOG.md	Documents the health/metrics event-loop starvation fix.
archive/v1/tests/unit/test_health_concurrency.py	Adds a regression test intended to detect event loop blocking during metrics gathering.
archive/v1/src/services/metrics.py	Avoids blocking the event loop during periodic system metrics collection.
archive/v1/src/api/routers/health.py	Avoids blocking the event loop in /health and /metrics endpoints by thread offloading + non-blocking CPU percent.

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