prompt: drop transient active/ copy of the reconciled pre_build prompt

lifecycle.py record folded and unlinked it, but its git-rm fallback left the
deletion unstaged, so the previous commit carried the file into active/. The
record in complete/2026/08/ is the sole copy.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K786tDX3EUywH86jGHYsfp

Author: claude