docs(roadmap): right-size to solo-maintainer reality; preserve vision in appendix

The former ROADMAP described a 7-year, $7.5M, 15-FTE programme (ISO/IEEE
standards, a documentary, a SaaS offering, "10,000+ users") for a repo
that is still discharging existence lemmas — the near-term framing was
disproportionate to the actual state.

Rewrite the body as an honest, dated-by-nobody solo roadmap grounded in
PROOF-STATUS.adoc: a truthful proof ledger (61 Coq + 52 Lean axioms
disclosed, only Coq+Agda actually reproduced, Z3 artifact absent), the
general reversibility<->CNO theorem MAA actually needs, the first three
OND obligations, and the CNO paper. The grand vision is retained verbatim
in scope but relocated to a clearly-labelled "Long-Horizon Vision
(aspirational, unfunded)" appendix so nothing is lost.

The genuinely-accurate OND two-pillar section is preserved.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015qwVESTcbfanY2iJPQNoSz

Author: claude