feat(viewer): browse individual events in a cluster

[krushiraj]

Clicking a dense event marker currently shows only the cluster's count, types, and time range. This adds a scrollable member list to the Event inspector so each event can be inspected without zooming until its marker separates.

Selecting a member keeps the cluster list and scroll position, updates the timeline marker and task/poll context, and exposes the existing field copy, correlation, and chart actions. Lists are bounded to 100 events per page. Selecting a different cluster resets the browsing state.

Refs #480. This addresses browsing within a selected cluster; it does not add a list of all trace events or new chart functionality.

Validation:

• Full Vitest suite, TypeScript checks, import-boundary check, and production UI build.
• cargo build -p dial9-viewer.
• Browser checks with the demo trace and a 205-event fixture: member selection, scrolling, pagination, keyboard activation, copying a field, creating a chart, and selection reset.
• Focused regressions cover equal names/timestamps, missing fields, task/poll resolution, pagination, and unpinning.

No Rust or trace-format changes.

Existing Node localStorage and Vite classic-script/externalization/circular-chunk warnings remain unchanged.

[rcoh]

do you have a screenshot or example video? Clicking on a cluster worked but I wasn't sure how to do the scrollable list you described

[krushiraj]

do you have a screenshot or example video? Clicking on a cluster worked but I wasn't sure how to do the scrollable list you described

I realized the scrollable container styling wasn't proper and had bad UX when you couldn't find it. So made some style changes and probably now its easy to see it.

Steps:

• Select a dense area in events pane
• I selected one cluster with 79 events
• On the right pane now I see the list of all 79 events
• I click on one of them and I see the data associated with it along with copyable values

Let me know if this looks good. If you had a different idea in your head or if you feel I read the issue wrong please let me know, will make necessary changes.

Thank you.

[rcoh]

hey sorry I can't seem to get this to work. How did you select the area? I shift selected. That then brings the flamegraph up (but it doesn't include spans during that time period).

If I click on a cluster, it jumps to one span in the cluster (which is fine) but I don't see any way to get to the other spans.

(I would say even if, as implemented, there is some way to get this to work and I am doing it wrong, the UX is very unintuitive so we should revisit)

[krushiraj]

issue-480-events.webm

@rcoh Please take a look at this video. Hopefully, it is clear now and ticks all 3 improvements suggested in #480

I'm just trying to understand if we both are on the same page here. Else please leave any clarifications or comments so that I can revisit and make necessary changes.