- Add modernc.org/sqlite dependency; write every sample to
/appdata/bee/metrics.db (WAL mode, prune to 24h on startup)
- Pre-fill ring buffers from last 120 DB rows on startup so charts
survive service restarts
- Ticker changed 3s→1s; chart JS refresh will be set to 2s (lag ≤3s)
- Add GET /api/metrics/export.csv for full history download
- Chart rendering: SymbolNone (no dots), right padding=80px so peak
mark line label is not clipped, min/avg/max appended to chart title
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>