## Summary

Adds duration labels next to each **span** bar in the trace waterfall timeline so users can read the duration at a glance without hovering the tooltip.

## Changes

### Timeline chart

- **TimelineChartRowEvents**
  - Renders a duration label (e.g. `12ms`, `1.2s`) **outside** each bar using `position: absolute`, so it doesn’t affect layout.
  - **Placement:** Label is on the **right** of the bar when most of the bar is before the timeline midpoint, and on the **left** when most of the bar is past the midpoint (based on bar center vs. `maxVal / 2`), to keep it in the emptier side.
  - Uses existing `renderMs()` from `TimelineChart/utils` for formatting.
  - Wraps each bar in a container with `overflow: visible` so the duration label is not clipped by the bar’s `text-truncate` (overflow hidden).
  - **TTimelineEvent** now supports optional `showDuration?: boolean`. When `false`, the duration label is hidden (default is to show).

### DBTraceWaterfallChart

- When building timeline events, sets `showDuration: type !== SourceKind.Log` so **log** rows do not show a duration (only spans do).

## Screenshots
<img width="1293" height="1187" alt="Screenshot 2026-03-11 at 18 36 34" src="https://github.com/user-attachments/assets/da04c317-a0bd-45d7-b0cc-f298564fb850" />


## Testing

- Open a trace with multiple spans and at least one correlated log; confirm duration appears beside span bars (left or right by midpoint) and does not appear beside log rows.

### References

- Closes HDX-3671