test(evals): Voyage's fixed test set as a plugin eval suite, expectations written before the first run

Seven `claude plugin eval` cases under evals/, runs: 1, deterministic graders
only (regex, tool_used, file_exists), no ablation. Each case tests one thing
Voyage promises and stops within minutes, headless:

- plan-requires-brief, plan-project-not-initialized, plan-rejects-unknown-export,
  review-requires-project: argument guards stop before any Agent or Write.
- plan-halts-without-phase-signals: a brief_version 2.1 brief without
  phase_signals halts /trekplan at the sequencing gate, before the swarm.
- review-validate-flags-bad-finding-id (known-positive) and
  review-validate-passes-clean-review (known-negative): /trekreview --validate
  names REVIEW_BAD_FINDING_ID on a planted bad ID and stays clean on a valid file.

Each case's expected_outcome is committed here, before the suite has run.
Fixtures are written by an inline scaffold.sh (needs --scaffold): chose inline
heredocs because a run cannot read the eval directory, and the add_dirs path
mapping is not documented. evals/results/ is ignored.

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

evals/plan-halts-without-phase-signals/prompt.md

@@ -0,0 +1,11 @@
+---
+description: "/trekplan on a brief_version 2.1 brief without phase_signals halts at the sequencing gate."
+expected_outcome: "brief-validator runs, reports BRIEF_V51_MISSING_SIGNALS, and /trekplan halts with the phase_signals hint; no Agent call (no exploration swarm), no plan.md."
+tags: [proevesett]
+runs: 1
+max_turns: 15
+timeout_seconds: 300
+allowed_tools: [Bash, Read, Glob, Grep, Write, Agent]
+---
+
+/voyage:trekplan --project proj