Add deployment markers to sitespeed graphs

[Claude]

Adds vertical dashed line markers to sitespeed performance graphs showing when deployments occurred, similar to Tideways deployment annotations.

Changes

• Added chartjs-plugin-annotation dependency (v3.1.0)
• Extract unique deployments from sitespeed data via computed property
• Render deployment markers as vertical lines with rotated labels on all three charts (Performance Metrics, Transfer Size, CLS)

Implementation

The sitespeed data already includes deploymentId foreign key references. The implementation:

1. Extracts unique deployments and their timestamps from the existing sitespeed measurements
2. Configures Chart.js annotation plugin to draw vertical dashed lines at deployment times
3. Displays deployment names as rotated labels in indigo color (rgba(99, 102, 241, 0.8))

const deploymentMarkers = computed(() => {
  if (!shop.value?.sitespeed) return [];
  
  const deploymentMap = new Map<number, { id: number; name: string; timestamp: number }>();
  
  shop.value.sitespeed.forEach((item) => {
    if (item.deployment?.id && !deploymentMap.has(item.deployment.id)) {
      deploymentMap.set(item.deployment.id, {
        id: item.deployment.id,
        name: item.deployment.name || `Deployment #${item.deployment.id}`,
        timestamp: new Date(item.createdAt).getTime(),
      });
    }
  });
  
  return Array.from(deploymentMap.values()).sort((a, b) => a.timestamp - b.timestamp);
});

Annotations are then applied to all chart instances via the Chart.js plugin configuration.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add deployment marker to sitespeed graphs</issue_title>
<issue_description>### Please describe the feature you would like to see implemented.

Similar to tideways deployment marker in the graphs

</issue_description>

Comments on the Issue (you are @claude[agent] in this section)

• Fixes Add deployment marker to sitespeed graphs #598