Extract Relevant Chunks for Candidate Cell

[RobinGummels]

Description:
Implement spatial filtering to load only those Zarr chunks whose spatial extent overlaps with the 10 km × 10 km candidate cell bounds.

Tasks:

• Transform candidate cell bounds from EPSG:5325 to native Sentinel-2 CRS (UTM)
• Determine which chunks intersect with candidate cell geometry
• Extract only relevant chunks using xarray slicing
• Verify spatial extent of extracted data matches candidate cell
• Optimize chunk selection to minimize I/O

Acceptance Criteria:

• Only chunks overlapping candidate cell are loaded
• Data covers entire 10 km × 10 km candidate cell area
• Spatial coordinates are correctly preserved
• Significant reduction in data volume compared to full scene loading