feat(intent): /trekplan halts without an approved intent; the approval is stamped on both paths

Veikart steg 1, økt 1 av 2. The three holes measured in the grounds:
(1) ## Intent / ## Goal were only checked for existence, (2) no approval
marker existed, (3) brief-approved was emitted only on the auto path.

- lib/validators/intent-approval.mjs: --check / --stamp. The marker is
  intent_approved_hash (sha256 over normalized ## Intent + ## Goal) +
  intent_approved_at. Editing either section after approval → STALE.
- /trekplan Phase 1 (Read the brief, both --brief and --project): runs
  --check and HALTS on BRIEF_INTENT_NOT_APPROVED / _STALE / _INVALID with
  the remedy spelled out; an unrunnable check halts too.
- /trekbrief Phase 4h (before the Phase 5 fork, asked even in --quick):
  shows Intent + Goal verbatim, AskUserQuestion Approve / Revise / Leave;
  only "Approve" runs --stamp. --stamp emits brief-approved, so the manual
  (default) path records it; the auto path's own emission is removed.
  New mode /trekbrief --approve <project-dir> = Phase 4h alone.
- README, CLAUDE.md, command-modes, HANDOVER-CONTRACTS §Handover 1,
  jsonl-schemas (trekbrief-stats gains intent_approved).

Valgt ingen brief_version-bump fordi skjemaendringen er rent additiv (to
valgfrie felt) og kravet sitter i /trekplan — enhver produsents brief kan
godkjennes via /trekbrief --approve uten produsentendring. Valgt eget
--check-kall i stedet for et flagg på brief-validator fordi --brief-stien
i dag ikke kjører validatoren i det hele tatt; et nytt validatorkall der
ville også stoppe på andre feil. Valgt fallback-datamappe = målestokkens
(plugins/data/voyage-…) fordi CLAUDE_PLUGIN_DATA er tom i Bash-miljøet og
event-emits egen fallback er stille skip — slik ble brief-approved 0 records.

What the marker does NOT prove (module header, command prose, contract):
same user, same machine — any session can stamp. A trace, not a signature.

Suite 1183 → 1201 (1199/0/2). Mutants M1–M5 (stale check off, check
always valid, gate line removed, stamp emits nothing, no normalization)
each fell ≥ 1 test. yardstick unchanged: RED, 1 of 3 countable.

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

CLAUDE.md

@@ -14,9 +14,9 @@ Voyage — a contract-driven Claude Code pipeline: brief, research, plan, execut
 
 | Command | Description | Orchestrator model |
 |---------|-------------|--------------------|
-| `/trekbrief` | Brief — interactive interview produces a task brief with explicit research plan; optionally orchestrates the pipeline | session |
+| `/trekbrief` | Brief — interactive interview produces a task brief with explicit research plan; ends with the operator approving `## Intent` + `## Goal` (`--approve <dir>` does only that); 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`. 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 | 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 |