feat(plan): plan 1.8, the plan gate, the design part and the plan-side checks

Wave 1, order 3 (P3 plan mode as the start, P2 design as its own part, P9
plan side). Contracts K3-K6 for the later merges.

- plan_version 1.8 (1.7 plans stay valid): Test first on every step, one
  End-to-end ("run the thing") step, optional Interface in / Interface out /
  Review focus fields, a ceremony class in the header (absent =
  architectural), and for architectural plans a ## Design part: module map
  without cycles, architecture rules that name their enforcer and the step
  that proves them, a requirements check asked as keep / change.
- K3 lib/validators/plan-gate.mjs: the critic verdict is recorded INSIDE the
  plan (Claude Code's plan approval hands a hook only the plan file's text),
  bound to the hash taken before the reviewers read it; 0 go / 1 stop / 2
  could not run; at most 3 critic rounds, then stop and ask.
- K5 lib/verification/arch-rules.mjs: runs the target repo's own
  dependency-cruiser or import-linter (installs nothing; 2 = not measured,
  never green); --prove --rule shows pass -> fail on a planted violation of
  that rule -> pass. Verified against dependency-cruiser 18.5.0 and
  import-linter 2.15; madge 8.0.0 left out (missed a planted .mjs cycle).
- K6 lib/verification/plan-scope-sweep.mjs: changed files no step names.
- /trekplan Phases 8-10: design part, bounded critic loop, the gate before
  "execute", a plan-mode path through ExitPlanMode (not yet run end to end
  inside plan mode). plan-critic 10 -> 12 dimensions; scope-guardian checks
  the ceremony.
- Fixed on the way: plan-validator and plan-review-dedup used the
  file://argv[1] main guard (no-op under a symlink or a space); CRLF plans
  failed every manifest; the dedup dropped finding severity.

Borrowed, credited in place: obra/superpowers, Kiro (docs), addyosmani/
agent-skills, mattpocock/skills, GitHub Spec Kit, bashebr/ai-native-sdlc,
Boris Cherny's public threads.

Suite 1497 (1495 / 0 / 2), 86 new tests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -28,7 +28,7 @@ Voyage — a contract-driven Claude Code pipeline: brief, research, plan, execut
 |---------|-------------|--------------------|
 | `/trekbrief` | Brief — interactive interview produces a task brief with explicit research plan; ends with the operator approving `## Intent` + `## Goal` (`--approve <dir>` does only that, then writes the trekbrief record); optionally orchestrates the pipeline | session |
 | `/trekresearch` | Research — deep local + external research, produces structured research brief. Opt-in `--engine {swarm\|deep-research}` delegates the external phase to Claude Code's built-in `/deep-research` workflow (swarm default) | session |
-| `/trekplan` | Plan — brief-reviewer, explore, plan, review. Requires `--brief` or `--project`; halts unless the brief's intent is approved (hash-bound, stale on edit). Auto-discovers `architecture/overview.md` if present | session |
+| `/trekplan` | Plan — brief-reviewer, explore, plan, review. Requires `--brief` or `--project`; halts unless the brief's intent is approved (hash-bound, stale on edit). Auto-discovers `architecture/overview.md` if present. Plan 1.8: `Test first:` per step + one `End-to-end:` step; a design part for `ceremony: architectural` (absent = architectural); critic loop of max 3 rounds, recorded in the plan, and `plan-gate.mjs` (0 go / 1 stop / 2 could not run) decides | session |
 | `/trekexecute` | Execute — disciplined plan/session-spec executor with failure recovery | session |
 | `/trekreview` | Review — independent post-hoc review of delivered code against the brief. Produces `review.md` with severity-tagged findings (Handover 6) | session |
 | `/trekcontinue` | Continue — resumes the next session of a multi-session voyage project. Reads `.session-state.local.json` (Handover 7) and immediately begins executing | session |
@@ -71,7 +71,7 @@ Full flag reference for each command (modes, `--gates`, `--profile`, breaking ch
 | brief-conformance-reviewer | opus | Brief conformance review (SC + Non-Goal traceability) |
 | code-correctness-reviewer | opus | Code correctness review (7 dimensions) |
 | review-coordinator | opus | Judge Agent — dedup + reasonableness filter + verdict |
-| plan-critic | opus | Adversarial plan review (10 dimensions) |
+| plan-critic | opus | Adversarial plan review (12 dimensions) |
 | scope-guardian | opus | Scope alignment (creep + gaps) |
 | session-decomposer | opus | Splits plans into headless sessions with dependency graph |
 | synthesis-agent | opus | Distills Phase-5/7 exploration outputs into a findings digest (NW3 PoC — **dormant**, not wired; delegating Phase 7 alone yields Δ main-context ≈ 0, see `docs/T1-synthesis-poc-results.md`) |