chore: drop two files swept into the a8 pin bump

0004678 was about the ontoenv 0.6.0a8 pin and closure_names, and its message
says only that. It also added two unrelated files, unmentioned and unnoticed
until the branch was pushed:

- buildingmotif/progressive_creation.py -- 137 lines of research WIP for
  ordering template population (greedy histogram over compatible triples).
  Imported by nothing, exported by nothing, covered by no test; it still has
  debug prints, a TODO, and a commented-out alternative approach.
- buildingmotif/exports/brick2af/examples/test.log -- a 10-line run log.
  Nothing else in that directory is tracked.

Deleting rather than rewriting 0004678: the branch is already on origin under
PR #396, and one honest deletion is cheaper to review than a force-push that
detaches the PR's commits.

progressive_creation.py is removed, not abandoned -- it exists on no other
branch, so bring it back from this commit's parent if the idea is picked up
again. It needs a home, a caller, and tests before it belongs in the package.

Author: gtfierro