Add reproducible Yaounde boundary and 30 m grid pipeline

[Omer-alt]

Summary

This PR establishes the reproducible spatial reference framework for the Yaoundé pilot study.

Changes

• records the HDX COD-AB Cameroon boundary source and provenance;
• selects Yaoundé I–VII using stable ADM3 P-codes;
• validates their union against the ADM2 Mfoundi boundary;
• constructs the administrative core, 5 km context buffer and convex hull;
• reprojects all processed geometries to EPSG:32632;
• creates an authoritative 30 m raster grid anchored at (0, 0);
• generates stable cell identifiers from global grid indices;
• exports core and context masks, a cell table and grid metadata;
• adds reproducible visual quality-control figures;
• adds automated provenance, geometry, CRS, grid and cell-identity tests;
• freezes the accepted grid specification as grid version 1.

Validation results

• Selected ADM3 units: 7
• ADM3 union vs ADM2 Mfoundi symmetric difference: 0.000000%
• Input CRS: EPSG:4326
• Analysis CRS: EPSG:32632
• Grid resolution: 30 m
• Grid anchor: (0, 0)
• Grid dimensions: 946 × 1278
• Core cells: 321,909
• Context cells: 879,666
• Vector core area: 289.728987 km²
• Rasterised core area: 289.718100 km²
• Relative vector/raster area difference: approximately 0.00376%
• Invalid final core geometry: No
• Core fully covered by context buffer: Yes

Reproduction

python -m pip install -e ".[dev]"
make build-grid
make visualize-grid
make test-grid