e04ca55374
The per-kind fixture guard claimed no-model scenarios need no session.jsonl, but the replay path requires one for ALL scenarios: runScenario() passes `fixtureFile: <dir>/session.jsonl` unconditionally and llm-replay's loadReplayScript() throws "fixture not found" when it is absent and no override replaces it. A no-model scenario ships a header-only session.jsonl that derives to an empty script. The guard + its comment now match that reality, so a future no-model scenario following them won't fail at subprocess startup.