- Add `getTaskLogs` API method and `taskLogs` react-query query
- Add `TaskLogPreview` component rendering last N lines of AI chat logs
  in a ScrollArea with auto-scroll-to-bottom
- Show log preview below state message in paused and failed task states
- Extract `useScrollAreaAutoScroll` hook shared with BuildingWorkspace
- Update Storybook stories with mock task log data

… preview

Add a left border to log lines with [user] and [agent] labels on type
transitions. Add a snapshot timestamp tooltip to the log header. Make
InfoTooltip title optional.