Create mockups for the Cesium timeseries navigation UI

[robyngit]

To enable navigation across time-enabled data layers in Cesium in Cesium maps, we need an interface for users to switch the time period they are viewing. We need mockups and mockup reviews before we start development on this feature.

considerations:

• Some layers will have a time component, and some will not.
• Layers could have different time periods (e.g., 2000–2020, 2010–2020, etc.).
• Layers could span different magnitudes of time (e.g., hours, days, months, years, decades, centuries).
• Some layers may represent a single point in time (e.g., 2020), while others may represent a time range (e.g., 2000–2020).
  • Will we support both models?
  • Will we display them differently in the UI?
• Some layers might benefit from a slider (continuous time), while others might work better with a dropdown (sparse or irregular times).
• Should the time selection sync across all visible time-enabled layers, or be independent per layer?
• What happens if a user selects a time when no data exists? (Options: show "no data" placeholder, disable unavailable times, fallback to nearest available time.)
• Should there be a global timeslider for all layers? Per-layer time controls inside the layer details panel? both?

early WIP mockups:

• A slider prototype (from a few years ago):
  

• A layer details panel idea (Figma prototype):
  
  Source