Story: Handle large datasets through tiling and caching

[edip-dev-01]

User story

As a user with large operational datasets, I want TerraFuse to stay responsive so that the COP remains usable under real data volumes.

Acceptance criteria

• Backend can pre-aggregate DGGS cells.
• Frontend requests only visible or relevant cell tiles.
• Expensive analysis results are cached by workspace, layer, resolution, and time range.
• UI shows progress for long-running jobs.