docs(roadmap): add phase orchestration system mirroring the reviewer audit workflow

Brings doc/roadmap/ to the same operational level as doc/reviewer/ by adding
the two missing structural files and updating existing docs to close the gap
identified in the system review.

New files:
- doc/roadmap/phase-orchestration.md  — master phase table (model assignments,
  session IDs, status, review-gate checklist); mirrors finding-orchestration.md
- doc/roadmap/session-prompts.md      — copy-paste-ready prompts for P1–P4
  (Haiku/Sonnet/Opus) + universal Opus review gate; mirrors reviewer/session-prompts.md

Updated files:
- CLAUDE.md: roadmap section now lists porting-status.md, phase-orchestration.md,
  session-prompts.md; reviewer section adds finding-orchestration.md and
  session-prompts.md; agentic-workflow section has direct "S3 is next / P1 is next"
  entry points so agents don't need to derive the next action from scratch
- doc/roadmap/phases.md: Current-focus table at the top (7 tracks, next session
  per track, gating); cross-links to geometry-central-comparison.md,
  software-landscape.md, complexity.md added in GC and 9b-analytic sections
- doc/roadmap/porting-status.md: snapshot date updated to 2026-05-31 (post S1+S2);
  test count replaced by reference to doc/api/tests.md; §4 gains four new solver
  rows (newton_core refactor, NewtonStatus enum, diagnostics, selectable clamp mode);
  §7 gains four new research-extension rows from S1/S2
- doc/roadmap/research-track.md: header companion-docs section links to
  novelty-statement.md, software-landscape.md, and phase-orchestration.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

doc/roadmap/research-track.md

@@ -7,6 +7,15 @@
 > port-tracking sheet `doc/roadmap/java-parity.md` so that the porting
 > work and the research work can be planned independently.
 >
+> **Companion documents:**
+> - [`doc/math/novelty-statement.md`](../math/novelty-statement.md) — why these
+>   contributions are novel and who the target audience is.
+> - [`doc/math/software-landscape.md`](../math/software-landscape.md) — how
+>   conformallab++ relates to libigl, geometry-central, and CGAL (relevant for
+>   deciding research vs. duplication at the boundary cases).
+> - [`phase-orchestration.md`](phase-orchestration.md) — model assignments and
+>   session prompts for implementing items in this document.
+>
 > **Created:** 2026-05-21, after a full doc audit that identified four
 > items previously mislabelled as "ports".  This document corrects the
 > record and extends it with the explicit research plan for Phase