fix: task status indicator not updating live in task view sidebar

[Kunal-Darekar]

What this fixes

Closes #80 (from upstream Netflix/metaflow-ui)

When viewing a task in the task view, the status indicator (the colored line next to each task name in the left sidebar) was not updating in real time as tasks finished. You had to reload the page to see the updated status, even though the timeline view updated correctly.

Root cause

TaskList.tsx uses react-virtualized's <List> component to render the sidebar task rows. react-virtualized aggressively caches row renders for performance — when task data updates arrive via WebSocket and the rows prop changes, the component sees new props but react-virtualized does not automatically re-render already-visible rows with the fresh data.

The old code had a window.scroll listener that called setScrollTop() on every scroll event. This worked as an accidental workaround — scrolling forced a re-render, which flushed the row cache and showed updated statuses. But if the user never scrolled, the status would never update.

Fix

Added a ref on the <List> component and call forceUpdateGrid() inside a useEffect that fires whenever rows changes:

useEffect(() => {
  listRef.current?.forceUpdateGrid();
}, [rows]);