feat(metrics): SQLite persistence + chart fixes (no dots, peak label, min/avg/max in title)

- 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>

audit/go.mod

@@ -1,6 +1,6 @@
 module bee/audit
 
-go 1.24.0
+go 1.25.0
 
 replace reanimator/chart => ../internal/chart
 
@@ -13,5 +13,14 @@ require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/go-analyze/bulk v0.1.3 // indirect
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	golang.org/x/image v0.24.0 // indirect
+	golang.org/x/sys v0.42.0 // indirect
+	modernc.org/libc v1.70.0 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+	modernc.org/sqlite v1.48.0 // indirect
 )