Statistics page: the statistics database's size, and a fullness bar on the disk tiles

The server section shows the statistics database's size (with its -wal and -shm) and how many answers the query log holds, linking to the dashboard's Storage panel; the disk tiles get the same bar as the dashboard. GET /stats/server has database {path, bytes, query_log_rows}.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/stats_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"io"
 	"log/slog"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -176,3 +177,24 @@ func TestStatsExploreAPI(t *testing.T) {
 		t.Errorf("storage %v", st["storage"])
 	}
 }
+
+// /stats/server reports the statistics database's size and the query log.
+func TestStatsServerDatabase(t *testing.T) {
+	ss, err := stats.OpenStore(filepath.Join(t.TempDir(), "stats.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ss.Close()
+	b := &stats.Batch{}
+	b.AddQueries([]stats.QueryRow{{Time: time.Now().Unix(), Client: "10.0.0.7", View: "internal", Name: "www.example.com", Type: "A", RCode: "NOERROR"}})
+	if err := ss.Commit(context.Background(), b); err != nil {
+		t.Fatal(err)
+	}
+	opts := stats.Options{QueryLog: true, StatisticsChannel: "127.0.0.1:1", TopN: 10, RetainMinute: time.Hour, RetainHour: 24 * time.Hour, RetainDay: 24 * time.Hour, RetainQueries: 7 * 24 * time.Hour}
+	e := newAPIEnv(t, stats.NewCollector(ss, opts, nil, slog.New(slog.NewTextHandler(io.Discard, nil))))
+	sv := e.do("GET", "/stats/server", e.token, nil, 200)
+	db, ok := sv["database"].(map[string]any)
+	if !ok || db["bytes"].(float64) <= 0 || db["query_log_rows"].(float64) != 1 {
+		t.Errorf("database %v", sv["database"])
+	}
+}