fix(webapp): hide queue header charts when there are no queues to chart

The four header chart tiles rendered even in the not-success states
(engine-version upgrade, no tasks) and when the list filtered to empty,
showing four empty 'No activity' cards above the blank state. Gate them
on the same queue set the table shows.

Author: kathiekiwi

apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.queues/route.tsx

@@ -625,59 +625,64 @@ function QueuesWithMetricsView() {
 
         {/* Env saturation, Backlog, Scheduling delay p95, Throttled viz — full-size, synced,
             drag-to-zoom line charts (Agent page pattern). Four chart tiles: 2x2 below lg, 4-up
-            from lg, derived from the tile count. `kind="charts"` bakes the fixed row height. */}
-        <ChartSyncProvider onZoom={zoomToTimeFilter}>
-          <MetricsLayout.Grid kind="charts">
-            {QUEUE_HEADER_TILES.map((tile) => (
-              <QueueEnvMetricChart
-                key={tile.id}
-                tile={tile}
-                timeRange={timeRange}
-                queueNames={chartQueueNames}
-                referenceLines={
-                  tile.id === "saturation"
-                    ? [
-                        {
-                          y: 100,
-                          label: `Limit ${environment.concurrencyLimit}`,
-                          labelPlacement: "outside" as const,
-                        },
-                        ...(environment.burstFactor > 1
-                          ? [
-                              {
-                                y: Math.round(environment.burstFactor * 100),
-                                label: `Burst ${Math.round(
-                                  environment.concurrencyLimit * environment.burstFactor
-                                )}`,
-                                labelPlacement: "outside" as const,
-                              },
-                            ]
-                          : []),
-                      ]
-                    : undefined
-                }
-                // Saturation and p95 "step over the line": a per-bucket overlay retraces only
-                // the over-threshold stretches in warning colour, so under-threshold values stay
-                // blue. (A gradient split can't do this reliably — an SVG objectBoundingBox
-                // gradient tracks the line's own bbox, not the y-axis, so a low/flat line reads
-                // as entirely warning-coloured.)
-                // All thresholded lines colour warning where they step over the threshold: the
-                // per-bucket overlay retraces only the over-threshold stretches, so the colour
-                // change tracks the axis crossing.
-                warningOverlay={
-                  tile.id === "saturation"
-                    ? { threshold: 100 }
-                    : tile.id === "p95"
-                      ? { threshold: 60_000 }
-                      : tile.id === "throttled"
-                        ? // Integer counts: threshold 0 warns once a bucket has ≥1 throttle.
-                          { threshold: 0 }
-                        : undefined
-                }
-              />
-            ))}
-          </MetricsLayout.Grid>
-        </ChartSyncProvider>
+            from lg, derived from the tile count. `kind="charts"` bakes the fixed row height.
+            Only when there are queues to chart: not-success states (engine-version, no tasks) and a
+            filtered-to-empty list leave chartQueueNames empty, where the tiles would just render
+            four "No activity" cards above the blank state. */}
+        {chartQueueNames.length > 0 ? (
+          <ChartSyncProvider onZoom={zoomToTimeFilter}>
+            <MetricsLayout.Grid kind="charts">
+              {QUEUE_HEADER_TILES.map((tile) => (
+                <QueueEnvMetricChart
+                  key={tile.id}
+                  tile={tile}
+                  timeRange={timeRange}
+                  queueNames={chartQueueNames}
+                  referenceLines={
+                    tile.id === "saturation"
+                      ? [
+                          {
+                            y: 100,
+                            label: `Limit ${environment.concurrencyLimit}`,
+                            labelPlacement: "outside" as const,
+                          },
+                          ...(environment.burstFactor > 1
+                            ? [
+                                {
+                                  y: Math.round(environment.burstFactor * 100),
+                                  label: `Burst ${Math.round(
+                                    environment.concurrencyLimit * environment.burstFactor
+                                  )}`,
+                                  labelPlacement: "outside" as const,
+                                },
+                              ]
+                            : []),
+                        ]
+                      : undefined
+                  }
+                  // Saturation and p95 "step over the line": a per-bucket overlay retraces only
+                  // the over-threshold stretches in warning colour, so under-threshold values stay
+                  // blue. (A gradient split can't do this reliably — an SVG objectBoundingBox
+                  // gradient tracks the line's own bbox, not the y-axis, so a low/flat line reads
+                  // as entirely warning-coloured.)
+                  // All thresholded lines colour warning where they step over the threshold: the
+                  // per-bucket overlay retraces only the over-threshold stretches, so the colour
+                  // change tracks the axis crossing.
+                  warningOverlay={
+                    tile.id === "saturation"
+                      ? { threshold: 100 }
+                      : tile.id === "p95"
+                        ? { threshold: 60_000 }
+                        : tile.id === "throttled"
+                          ? // Integer counts: threshold 0 warns once a bucket has ≥1 throttle.
+                            { threshold: 0 }
+                          : undefined
+                  }
+                />
+              ))}
+            </MetricsLayout.Grid>
+          </ChartSyncProvider>
+        ) : null}
 
         {success ? (
           <MetricsLayout.Content>