Automatic case generation from open European data

[HugoFara]

Europe has no LANDFIRE equivalent, so building a case needs a lot of manual work (#167, #169). Proposal: one entry point that builds a case from open data.

ff.new_case(bbox=(...), date="2023-08-10T14:00Z")

Sources: Copernicus DEM, CORINE or ESA CCI land cover, and ERA5 wind. This is mostly Python glue; no C++ changes.

Main gap: no land-cover-to-fuel mapping exists anywhere in the repo. FUELCOVER.md lists the land-cover classes but never maps them to fuel indices. Building that mapping needs expert judgement, and it would be worth publishing on its own.

Steps:

1. Fix genForeFireCase.py (genForeFireCase.py is documented in four places but is not in the repository #167).
2. CORINE → fuel mapping.
3. Copernicus DEM fetch by bounding box, with caching.
4. ERA5 wind (needs the 4-D fix from genForeFireCase.py is documented in four places but is not in the repository #167).
5. new_case(), validated with A landscape validation command #169.

Steps 1–2 are useful even if the rest is never built.

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Drafted with Claude Opus 5, reviewed by a maintainer.