Aligns with the other lib-asset prototype packages (fa-starter,
subterrain) where baked atlases ship with the lib instead of being
regenerated per-consumer. Removes a runtime atlas-baker dependency
for downstream consumers (vagrant-skeleton, map-editor) — they can
load the JSON+PNG pair directly after a plain install-reference
stage without invoking Python+Node toolchains.
Variants committed: blob_concave, blob_diagonal_cut, blob_organic,
blob_rectilinear, blob_rect_grass, blob_rect_stone, blob_rect_wood,
blob_testbench. Re-bake via scripts/bake.sh when sources change.
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