Server-side analytics for Cloud Playout channels

Cloud Playout analytics have moved off the client-side polling pipeline onto a server-side analytics service.

• Channel analytics graphs render with consistent X-axis lines and gridlines for easier reading.
• A comparison overlay lets you compare two time ranges (e.g., today vs. last week) with matched tooltips.
• Empty-state handling has been added so newly-created channels show a “no data yet” view instead of a flat-zero graph.
• Tooltip values for the comparison graph are calculated correctly and no longer show stale values when the cursor leaves the chart.
• The player domain URL used inside analytics dashboards is now resolved dynamically per environment.

The previous client-side aggregation has been retired; existing saved time ranges and channel filters carry over.