perf(clickhouse): Phase 2 legacy governance — TTL cleanup, unified pool, MV, ops API

- Replace retention ALTER DELETE with MATERIALIZE TTL; use TRUNCATE for delete-all
- Remove GORM ClickHouse pool; migrate user access log reads to ChConn
- Drop query-side trim(remote_addr); enable wait_for_async_insert=1
- Add of_node_traffic_hourly MV and dashboard traffic trend fallback
- Add GET /admin/status/clickhouse operational metrics endpoint

internal/apps/openflare/observability/analytics.go

@@ -257,6 +257,28 @@ func buildHealthSummary(
 	return summary
 }
 
+// BuildTrafficTrendPointsFromHourly builds 24h traffic trend buckets from hourly rollups.
+func BuildTrafficTrendPointsFromHourly(now time.Time, hourly []*model.OpenFlareTrafficHourly) []TrafficTrendPoint {
+	start := trendWindowStart(now)
+	points := make([]TrafficTrendPoint, observabilityTrendBuckets)
+	for index := range points {
+		points[index].BucketStartedAt = start.Add(time.Duration(index) * time.Hour)
+	}
+	for _, row := range hourly {
+		if row == nil {
+			continue
+		}
+		index, ok := trendBucketIndex(row.Hour, start)
+		if !ok {
+			continue
+		}
+		points[index].RequestCount += row.RequestCount
+		points[index].ErrorCount += row.ErrorCount
+		points[index].UniqueVisitorCount += row.UniqueVisitorCount
+	}
+	return points
+}
+
 // BuildTrafficTrendPoints builds 24h traffic trend buckets.
 func BuildTrafficTrendPoints(now time.Time, reports []*model.OpenFlareRequestReport) []TrafficTrendPoint {
 	start := trendWindowStart(now)

internal/apps/openflare/observability/analytics_test.go

@@ -10,6 +10,23 @@ import (
 	"github.com/Rain-kl/Wavelet/internal/model"
 )
 
+func TestBuildTrafficTrendPointsFromHourlyBucketsByHour(t *testing.T) {
+	now := time.Date(2026, 7, 2, 15, 30, 0, 0, time.UTC)
+	hourly := []*model.OpenFlareTrafficHourly{
+		{
+			NodeID:             "node-a",
+			Hour:               now.Add(-2 * time.Hour).Truncate(time.Hour),
+			RequestCount:       12,
+			ErrorCount:         1,
+			UniqueVisitorCount: 4,
+		},
+	}
+	points := BuildTrafficTrendPointsFromHourly(now, hourly)
+	if len(points) != observabilityTrendBuckets {
+		t.Fatalf("BuildTrafficTrendPointsFromHourly() len = %d, want %d", len(points), observabilityTrendBuckets)
+	}
+}
+
 func TestBuildTrafficTrendPointsBucketsByHour(t *testing.T) {
 	t.Parallel()
 

internal/apps/openflare/observability/node_logics.go

@@ -134,6 +134,10 @@ func GetNodeObservability(ctx context.Context, id uint, query NodeQuery) (*NodeV
 	if err != nil {
 		return nil, err
 	}
+	trafficTrend := BuildTrafficTrendPoints(now, reports)
+	if trafficHourly, hourlyErr := model.ListOpenFlareTrafficHourlySince(ctx, node.NodeID, now.Add(-24*time.Hour)); hourlyErr == nil && len(trafficHourly) > 0 {
+		trafficTrend = BuildTrafficTrendPointsFromHourly(now, trafficHourly)
+	}
 
 	view := &NodeView{
 		NodeID:          node.NodeID,
@@ -147,7 +151,7 @@ func GetNodeObservability(ctx context.Context, id uint, query NodeQuery) (*NodeV
 			Health:        buildHealthSummary(latestMetricSnapshot(snapshots), latestTrafficReport(reports), events),
 		},
 		Trends: NodeTrends{
-			Traffic24h:  BuildTrafficTrendPoints(now, reports),
+			Traffic24h:  trafficTrend,
 			Capacity24h: BuildCapacityTrendPoints(now, snapshots),
 			Network24h:  BuildNetworkTrendPoints(now, snapshots, openrestyObs),
 			DiskIO24h:   BuildDiskIOTrendPoints(now, snapshots),