More elegant way to access `v1` programmatically?

I am using projective or conformal bases, such as
```Julia
julia> S = S"∞++"
julia> B = Λ(S)
```

I want to write dimension-generic code, and want to access the `i`-th basis vector. Unfortunately, Grassmann counts starting from `v∞`, so that `v₁` is `B.v(2)` etc. It would be more convenient if `B.v(1)` returned `v1`, independent of whether `v∞` or `v∅` were present. I currently have to write `B.v(i+1)` or `B.v(i+2)`, depending on the basis.

I realize this would be a breaking change, and obviously this is not an urgent feature request.

Start by locating the Julia implementation and tests for the `B.v` accessor, then inspect how bases containing `v∞` or `v∅` determine vector indexing. Done means dimension-generic calls such as `B.v(i)` consistently return the i-th ordinary basis vector, with the breaking behavior documented and covered by tests.

Written by the indexing model from the issue text.