perf(runtime): add persistent production monitor

[Boym323]

Summary

• add bounded 60-second runtime telemetry for process, event-loop, GC, DB settlement, hot paths, circuit state, retention, and availability
• persist stable warning/degraded/critical incident ledger without raw payloads
• move the systemd ADSB watchdog from full system status to a lightweight health probe
• document the production V5 soak/OOM investigation in English and Czech

Evidence

• npm test
• npm run typecheck:prepared
• npm run lint (pre-existing warnings only)
• npm run docs:check
• npm run features:check