chore: untrack agent-scratch files committed before the gitignores landed

.lavish/ and .superpowers/sdd/ are gitignored working dirs; these three files
(final-review.html, task-7/task-9 reports) were committed before the ignores and
remained tracked. Content stays on disk; only the index entries are removed.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dmealing