Variable dropDegenerateTrianglesConst

dropDegenerateTriangles: Fix = ...

Auto-fix for GEOMETRY_DEGENERATE_TRIANGLES — rewrites geom.indices to drop every triangle that has repeated indices or whose cross-product magnitude is below the area epsilon.

Touches indices only — vertex arrays (positionsCompressed / normalsCompressed / uvsCompressed / edgeIndices) are left intact, so geometries that survive the filter still have a valid AABB and stable vertex slots. The companion compactUnusedVertices can then sweep up any vertex slots that became unused as a side-effect.

Idempotent: returns {fixed: false} when no triangles meet the degenerate criterion. The geometry's indices field is mutated in place via typed cast (the same pattern addMissingUVs uses for uvsCompressed).