docs: merge main, renumber security audit profile P-023 -> P-024

PR #171 (architecture guard, Own.Arch) merged to main first and took
P-023; the security audit profile proposal moves to the next free
number. Index row re-linked accordingly.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0113xowoaqfUnPEXxxi15Gpm

Author: claude