Read app metrics

Recent per-app metrics from its server: container state (running/restarting/exited), restart count, CPU percent, memory bytes against its limit, and volume bytes — minute-bucketed over the last 24 hours. The state "unknown" means the agent has not reported recently; unknown is never "healthy". Numbers only — the report the agent sends cannot carry configuration or secrets. Since 25 September 2026, minute points live 48 hours, a daily rollup consolidates closed hours (>24h) into an hourly table kept 90 days, reads past 24 hours merge hourly and minute rows with every point marking its resolution, the minutes range grows to 129600, and CPU becomes the sample-weighted bucket average when the agent reports cpu_avg_pct/cpu_samples (no agent release sends them yet, so current agents keep one instant sample per minute, samples=1).