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>

tests/fixtures/jsonl-schemas.md

@@ -19,7 +19,7 @@
 
 | schema_id | fields | writer_path | line_ref | v4.1 additive | PII |
 |-----------|--------|-------------|----------|---------------|-----|
-| trekbrief-stats | ts, task, slug, mode, interview_turns, review_iterations, brief_quality, research_topics, auto_research, auto_result, project_dir | commands/trekbrief.md (orchestrator-emit Phase 7) | trekbrief.md:657-672 | profile, phase_models, profile_source | none |
+| trekbrief-stats | ts, task, slug, mode, interview_turns, review_iterations, brief_quality, research_topics, auto_research, auto_result, intent_approved, project_dir | commands/trekbrief.md (orchestrator-emit Phase 7) | trekbrief.md:657-672 | profile, phase_models, profile_source | none |
 | trekresearch-stats | ts, question, mode, scope, engine, slug, project_dir, brief_path, dimensions, dimensions_baseline, dimensions_baseline_preserved, effort, conv_turns, empty_turns, unique_sources, agents_local, agents_external, gemini_used, confidence, contradictions, open_questions | commands/trekresearch.md (orchestrator-emit Stats tracking) | trekresearch.md:634-676 | profile, phase_models, parallel_agents, external_research_enabled, profile_source | none |
 | trekplan-stats | ts, task, mode, slug, brief_path, project_dir, codebase_size, codebase_files, agents_deployed, deep_dives, research_briefs_used, research_scout_used, critic_verdict, guardian_verdict, outcome | commands/trekplan.md (orchestrator-emit Phase 12) | trekplan.md:805-826 | profile, phase_models, parallel_agents, profile_source | none |
 | trekexecute-stats (Phase 9 record) | ts, plan, plan_type, mode, result, steps_total, steps_passed, steps_failed, steps_skipped, failed_at_step | commands/trekexecute.md (orchestrator-emit Phase 9) | trekexecute.md:1479-1494 | profile, phase_models, profile_source | none |