chore(www): migrate root .well-known/ to www/.well-known/ (#79)

Completes the estate-wide `.well-known` migration — the branch was
created but no PR was opened for this repo. Pure file renames (0
insertions, 0 deletions), matching the 234 already-merged PRs in this
wave.

Co-authored-by: stage5-sweep <stage5-sweep@users.noreply.github.com>

Author: hyperpolymath