fix(models): correct contributor guard, 1M context, docs for muse-spark-1.3
- model_data_policy_guard: name the triggering -contributor model instead
of hardcoded 1.2; per-version verified price tables (1.3 standard
$1.25/$4.25 via OpenRouter live metadata; cached figures 1.2-only)
- model_metadata: muse-spark-1.3 + muse-spark family at 1048576 (OpenRouter
verified 2026-09-02) with pre-catalog stale-cache keys so 256K-fallback
sessions self-heal
- docs: contributor-tier notes cover 1.2 + 1.3
- tests: 1.3 guard regression, muse stale-cache guard, live-catalog mirror
gains 1.3-contributor-free (confirmed on live relay)
143 tests pass (guard, selection guards, opencode catalog, model_metadata);
ruff clean.
cfa7e72c9e